GLAIVE weapon design system for the d20 System

d20 version and article by Tail Kinker ( )

Based on GLAIVE, by Tbone.

Call me a traitor. I don’t care. I’ve grown to really like the d20 system. Doesn’t mean I’ve given up on GURPS. Far from it; my GURPS library remains central to my gaming needs. Not just for running, but as a bridge to other systems – like d20.

But the weapon system for Dungeons and Dragons is just plain dreadful. So here I go, trying to update it.

This system will not faithfully reproduce the weapons from Dungeons and Dragons, but if used consistently, will give a good play-balance while fixing some of the more painful moments in game play.

Melee Weapons

This section primarily covers melee weapons, though some of the characteristics described below affect missile weapons as well. GLAIVE d20 does not make any distinctions between Simple, Martial or Exotic weapons; that’s up to the Game Master. (But certain sections will label a weapon Exotic, depending on variables.)

As with GLAIVE for GURPS, there are a few characteristics of weapons that need to be defined:


Longer weapons hit harder, but only to a point. The biggest advantage that a long weapon gives the wielder is more reach. Length in GLAIVE d20 is measured in feet.


This is the biggest factor in a weapon’s impact. The more mass a weapon has, the more force can be put behind it. Weight in GLAIVE d20 is measured in pounds.


This is a ‘free’ element of design, but it does affect the weapon’s performance, albeit to a lesser degree than weight or length. Essentially, Grip adds up to the number and placement of hands needed to wield the weapon. Grip varies from weapon to weapon, and certain lengths are required for certain grip styles.


Unbalance ranges from one (well-balanced) to three (quite unbalanced) under normal circumstances, though you can define Unbalance outside of this range, or even fractionally (such as a scimitar, which might be described as having a Unbalance of 1.5). Lower Unbalance values make a weapon easier to use, but greater Unbalance values give a weapon greater striking performance.


The primary difficulty in porting GLAIVE to d20 is simple: in GURPS, damage is a function of Strength, modified by weapon; in d20, weapon damage is a function of weapon, modified by Strength. This is not an insurmountable problem, but due to the fact that it is a consistent problem, right through the entire system, it’s one I have to adapt to rather than ignore. Throughout this version of GLAIVE, weapons are given Damage Codes. Consult the table below to determine the dice rolled for the damage code in question.

Damage Code


Damage Code


0 or less


























13 or more


Damage Types

The conventional GURPS Crushing / Cutting / Impaling categories of damage easily translate to the d20 system’s Bludgeoning / Slashing / Piercing. Slashing damage will multiply the Damage Code by 1.25 (before rounding), and Piercing Damage will multiply Damage Code by 1.5 (again, before rounding). Each weapon will have both a Thrusting damage and a Swinging damage.

The table below shows the Critical values (Threshold and Multiplier) for each combination of Thrust and Swing, and Bludgeoning, Slashing and Piercing damage.

Damage Type




20 / x2

20 / x2


20 / x2

19-20 / x2


20 / x3

19-20 / x3

Wield Strength

This is the Strength required to use the weapon effectively. It is not a minimum Strength, but a character with significantly less Strength than the weapon’s Wield Strength is going to have problems. The Wield Strength for any weapon is equal to the square root of (weight x 30), dropping fractions. Don’t worry if this seems too high, though.


This is a measure of the time required to ready a weapon. It does not affect Initiative scores, but instead affects the number and type of Actions required to ready the weapon for use.

Attack Bonus / Penalty

Certain weapons will inherit a bonus or penalty based on their size and grip. Wield Strength may also affect a weapon’s Attack Bonus or Penalty, but this is handled on a character-by-character basis.

Thrust Statistics

Now it’s time to actually get some performance statistics on your weapon.

Damage Code = square root of (weight x 2)

If the weapon is designed to be used two-handed, multiply its Damage Code by 1.25. Drop all fractions. The Damage Code for a piercing weapon cannot exceed twice its length in feet. So no matter how heavy a three-foot spear is, its maximum Damage Code is six.

Recovery = Weight x 4

Multiply Recovery by 2/3 if the weapon is held near the centre with one hand, or for a weapon held with both hands near the end. Halve the Recovery value of a weapon if it is used with two hands set widely apart (as with a spear or pole arm).

A weapon that is two to three feet long will suffer an Attack Penalty of -1 when wielded two-handed, unless the weapon is Exotic. A weapon less than two feet long will suffer an Attack Penalty of -2 when wielded two-handed, Exotic or not. Note that these penalties apply whether or not a weapon is designed for two hands.

Swing Statistics

Swinging a weapon will boost its damage, but only to a certain point. To calculate the Damage Code for a swung weapon, follow this procedure:

Start with the weapon’s length, or three feet, whichever is lower. This is the weapon’s effective length. If the weapon is longer than three feet, calculate the “dropped” length and set it aside for the moment.

Now calculate the Swing Effect of the weapon:

Swing Effect = ((effective length x unbalance) + 3) / 2

The Swing Effect is basically a Weight multiplier thrown into the Damage equation.

Damage Code = square root of (Weight x Swing Effect x 2)

Remember that “dropped length” from before? It’s used to calculate the weapon’s Recovery.

Recovery = (Weight x Swing Effect x 2) + (Dropped Length x Weight)

Swing Recovery cannot be lower than Thrust Recovery. As with Thrusting, multiply Recovery by 2/3 if the weapon is held near the centre with one hand, or for a weapon held with both hands near the end. Halve the Recovery value of a weapon if it is used with two hands set widely apart (as with a spear or pole arm).

Ready Time

The Ready time for a weapon is based on both Recovery and the character’s Strength, so you’ll need to calculate it for each character and weapon.

First, you need to find the Modified Recovery for the weapon, based on the character’s Strength. Here’s where the Wield Strength for the weapon comes into play. Divide the Wield Strength by the character’s Strength, and consult the following table:

Wield STR / Character STR


Less than 1

No Modifiers

1 to 1.5

Recovery x 1.5

1.5 to 2

Recovery x 2, Attack Penalty -2

2 to 3

Recovery x 3, Attack Penalty -4

Greater than 3

Weapon cannot be effectively used

Ready Penalty = Modified Recovery / Strength

Drop all fractions.

What does the Ready Penalty do? Basically, it inflicts an Attack Penalty on all attacks after the first!

When a weapon is completely Readied (say, at the start of a fight), its Ready Penalty is zero. After any attack, the weapon’s Ready Penalty becomes the value calculated above. This is not cumulative; no matter how many times a weapon is used, its Ready Penalty remains constant. Actions may be used to reduce a Ready Penalty, but never to the point that the Ready Penalty becomes a bonus!

Action Type

Ready Penalty Reduction

Move Action


Attack Action


Full-Round Action


If your Ready Penalty is worse than -8, you cannot attack with the weapon. Furthermore, it will probably take you more than one full round to ready it. Unlike Ready Penalties, Penalty Reductions are cumulative. Two full-round Ready actions will reduce a Ready Penalty by sixteen.


A weapon, if held in a hand, has a minimum reach of one square. That is, you can attack any target within any adjacent square of your character. But some weapons might reach out farther. Add the length of the weapon to 1.5 feet. For every five full feet this totals, the weapon has a reach of one additional square. Why the 1.5 feet? It’s half the length of a character’s arm. Why only half? Because you still have to hold onto the weapon, and it’s unlikely you will wish to extend your arm to its fullest in the middle of a fight!

Optional Rule: The Lunge

But what if you want to extend the full length of your arm?

This is the classic manoeuvre of the fencer: The Lunge. The attacker extends the weapon to its limit, and steps into the attack. This gains him two additional feet of reach. If this puts you into the next five-foot category, then congratulations: your weapon can reach one additional square. But the penalties are ugly: The attacker suffers an Attack Penalty of -2, and his Ready Penalty is doubled (or increased to -1, if it is normally zero). 


So let’s put these rules to the test.

Druul Slugmunch, a Half-Orkish Barbarian, has a Strength of 17. He selects his first weapon: A three-foot, four pound mace, with an Unbalance of 3.

When thrusting with this weapon, the Damage Code will be the square root of (4 x 2), or 2.83. We drop fractions, so that becomes a Damage Code of 2, or a Damage of 1d4. But Druul decides that he will always thrust with the mace held in two hands, one at the base, the other at the head. So his Damage Code (with fractions intact!) is multiplied by 1.25. This puts it up to 3.5, rounded down to 3, or a Damage Code of 1d6.

The Recovery Value of the mace is normally (4×4), or 16, but this is halved to 8 due to his Grip. Its Wield Strength is equal to the square root of (4 x 30), or 10.95. Again, we’re dropping fractions, so the Wield Strength is 10. This is less than Druul’s Strength, so he takes no modifiers to Recovery. The Ready Penalty for the weapon is 8 / 17, or 0.47, or, dropping fractions, zero.

So Druul can take a poke with the mace, inflicting 1d6 damage plus his Strength Modifier, and can do it basically forever. Due to the length, however, he will suffer an Attack Penalty of -1.

But what if he swings it?

The effective length of the weapon is three feet. So his Swing Effect is ((3 x 3) + 3) / 2, or 6. Plugging this into the Damage formula, we get the square root of (3 x 6 x 2), which is 6. This is a one-handed damage of 1d10 plus his Strength Bonus. There is no Dropped Length, so his Recovery is (3 x 6 x 2) + (0 x 3), or 24. So his Ready Penalty will be (24 / 17), or 1.41, rounded to 1. So each swing after the first will suffer an Attack Penalty of -1, until he takes at least one spare Attack to Ready the weapon.

Druul could choose to swing the mace two-handed, but his Damage Code would only go up to (6 x 1.25), or 7.5. This is a Damage of 1d12 plus Strength bonus. Since he’d likely swing it with both hands at the end, his Recovery would drop to (2/3 x 24), or 16. Then he could wield the mace with no Ready Penalty. Of course, he’s taking a -1 on every attack, due to the length of the weapon, so he probably won’t do that.

Since the mace is a Bludgeoning weapon in both attack forms, its Critical values are 20 / x2.

Now Druul selects a new weapon: a nine-foot, ten-pound spear. Why exactly would you want a nine-foot spear? Because when added to the 1.5 feet of a character’s arm length, this gives you a reach of three squares!

With a Wield Strength equal to the square root of (10 x 30), totalling 17.32, not even Druul is not going to be comfortable wielding this monster one-handed. So he decides to use a two-hand, wide grip on the spear. Since the spear is over three feet long, there is no Attack Penalty for using it two-handed.

Thrust Damage Code will equal the square root of (10 x 2), or 4.47. Multiply this by 1.25, because Druul is using it two-handed, then multiply it by 1.5 because a spear is Piercing. The result is 8.38, rounded down to 8. So his basic Thrusting Damage will be 2d6. The weapon’s Recovery is (10 x 4), halved due to his Grip, for a total Recovery of 20. So his Unready Penalty will be (20 / 17), or 1.18, rounded down to 1. When thrust for impaling damage, the spear’s Critical values will be 20 / x3.

A spear is reasonably well balanced; perhaps a 1.5 Unbalance is appropriate. If Druul chooses to swing the weapon, his Swing Effect will be ((3 x 1.5) + 3) / 2, for a total of 3.75. His Damage Code when swinging will be the square root of (10 x 3.75 x 2), or 8.66. So his Swing Damage will also be 2d6. But the spear has six feet of dropped length! So its Recovery will be (10 x 3.75 x 2) + (6 x 10), or a monstrous 135! That’s a Ready Penalty of (135 / 17), or 7.94! So Druul will take a -7 penalty for his next attack with the spear after a swing, unless he wants to spend a full round readying the weapon! Add that to the Swing/Bludgeoning Critical value of 20 / x2, and there’s no way he’s going to swing this huge stick! 

Now Aleveras, a Human Sorcerer with a Strength of 9, picks up the mace. The weapon’s Damage will not be modified; Aleveras’ Strength Bonus is much lower than Druul’s, however, so his effective Damage will be lower due to a lower Strength Modifier (-1 instead of +3). But how does his Strength of 9 rack up against Druul’s 17 for readying purposes?

The Wield Strength of the mace is 10, so Aleveras will suffer a 50% increase in the mace’s Recovery value. Aleveras chooses to use the same two-hand grip that Druul favours, so his Modified Recovery will be (8 x 1.5), or 12. Aleveras’ Ready Penalty will be (12 / 9), or 1.333, rounded down to 1. Add to that the fact that he’s taking an Attack Roll Penalty of -1, and Aleveras is not nearly as handy with this mace as Druul.

Aleveras could have simply swung the mace, so his Modified Recovery would be (16 x 1.5), or 24. But his Damage would fall to 1d4, and his Ready Penalty would rise to (24 / 9), or 2.666, rounded down to -2. But at least he’d have that pesky Attack Bonus due to two hands on a short weapon removed.

When he switches to swinging the mace, Aleveras’ Recovery will be (24 x 1.5), or 36. So his Ready Penalty will become -4, and he will have to spend an Attack Action (or two Move Actions) to ready the mace in order to counter this penalty. He could put both hands on the mace, raising its Damage to 1d12. Doing this would drop his Recovery to 24, and his Ready Penalty down to -2. Much more manageable. But then that Attack Penalty of -1 would crop up again.

And if Aleveras picks up that monstrous spear, things only get worse. The spear’s Wield Strength is 17.32. Divide this by Aleveras’ Strength, and you get 1.924. This means that Aleveras’ Recovery will be doubled, to 40, and he’ll suffer a -2 to all Attack Rolls due to the mass of the weapon. So his Ready Penalty when thrusting with the spear will be (40 / 9), or 4.44, rounded down to -4. If he’s silly enough to swing the spear, his Recovery will be 270, and his Ready penalty will be -30!

Aleveras would be much happier with a smaller, lighter weapon: a dagger, one foot long and weighing two pounds, with an Unbalance of 1.

The dagger would have a Wield Strength equal to the square root of (2 x 30), or 7.75, rounded down to 7. This is lower than Aleveras’ Strength, so he’s in business. Its damage would be low – only the square root of (2 x 2), or 2. But that value is multiplied by 1.5, because a dagger is a Piercing weapon. This brings the thrusting Damage Code up to 3, or a Damage of 1d6 plus Strength Modifier. The Recovery of the dagger on a thrust would be (2 x 4), or 8. For Aleveras, this is still lower than his Strength, so his Ready Penalty would be zero. The weapon would have a total reach of 2.5 feet, with a Lunge of 4.5 feet. Either way, it has a Reach of one square, so there’s no sense in using a Lunge.

What if Aleveras swings the dagger? Its Effective Length is one foot, so its Swing Effect is ((1 x 1) x 3) / 2, or a total of 1.5. Therefore, its base Damage Code will be the square root of (2 x 1.5 x 2), or 2.45. Since a dagger has a cutting edge, this is boosted to 3.06, or a Damage of 1d6 plus Strength Modifier. Its Recovery when swung would be (2 x 1.5 x 2) + (0 x 2), or 6. This is boosted to 8, since it’s lower than the Thrust Recovery. So he still has a Ready Penalty of zero. Much more suitable to the Sorcerer.

Aleveras could use the dagger in two hands, but the damage bonus would be negligible, and the poor fool would suffer an Attack Penalty of -2. Being a Sorcerer, he’s not stupid, so he uses it in one hand.

How would you list these weapons? As follows:

Dagger: Length 1′, Weight 2 lbs., Wield STR 7, Thrust P/1d6, Swing C/1d6, Recovery 8, Critical 20 / x3 or 19-20 / x2.

Heavy Spear: Length 9′, Weight 10 lbs., Wield STR 17, Thrust P/2d6, Swing B/2d6, Recovery 40 / 135, Critical 20 / x3 or 20 / x2. Two-Handed

Mace: Length 3′, Weight 4 lbs., Wield STR 10, Thrust B/1d4 (1d6), Swing B/1d10 (1d12), Recovery 16 / 24, Critical 20 / x2

Hurled Weapons

All of the above applies as much to hurled weapons as it does to melee weapons, save for two important differences.

First, all hurled weapons inflict Thrust damage on impact. This is due to the fact that they must either be thrown to impact point- or blade-first, or because they tumble in flight (expending some energy on the rotation).

Second, hurled weapons have a Range Increment. The Range Increment is calculated based on the weight of the weapon and the thrower’s strength. Remember that hurled weapons have a maximum range of five Range Increments.

Range Increment = (Strength x 6) / (Weight + 3)

Recovery is irrelevant to hurled weapons, for obvious reasons.

So Aleveras decides to throw his dagger at a fleeing Kobold. The Kobold has gotten 30 feet away from him. His Range Increment is equal to (9 x 6) / (2 + 3), or 10.8 feet, rounded down to 10 feet. So the Kobold is three Range Increments away, and Aleveras will suffer an Attack Penalty of -4 due to range.

Druul’s mace is heavier, but his Strength is greater. Should he throw his mace at the same Kobold, his Range Increment will be equal to (17 x 6) / (2 + 4), or 17 feet. Thus, the Kobold would be two Range Increments away, and Druul would have an Attack Penalty of only -2 due to range.


Hurled weapons are rather simple; bows are considerably more complicated.


Bows for use in Dungeons and Dragons are made of two types of material: wood, or a composite of wood and other materials. Composite bows are stronger, hit harder, and are quite a bit more expensive.


Just as with melee weapons, the length of a bow matters. A typical bow will be between three and five feet length. The English Longbow was a six-foot weapon; the Daikyu of the Samurai was seven feet long. In the case of crossbows, the bow length is across the staves, not the length of the stock.

Load Strength

An archer uses his Strength to draw a bow, to the limits of either his or the bow’s strength. Each bow has a Load Strength, that determines the maximum strength that may be used to draw the bow. This is the ‘draw weight’ of the bow.

Wooden bows will have a Load Strength equal to three per foot of bow; composite bows will have a Load Strength of four per foot. These values are doubled for crossbows.

Bow Weight and Wield Strength

The formula for the typical weight of an arm bow, either wooden or composite, is:

Weight = (Length x Strength) / 15

Double this weight for a crossbow. Use the weight value to determine the Wield Strength for the bow, as discussed for melee weapons. Recovery modifiers won’t matter for a bow, but attack penalties will. Note that with an arm bow, only one arm supports the weight, so arm bows are considered one-handed for purposes of Wield Strength. But crossbows are supported with two arms at wide grips. This means that a person with a lower Strength than the Wield Strength of the bow can still use it. Since Recovery is not used with bows, simply divide the Wield Strength for crossbows by two.

Firing Strength

The Strength of the person using the bow must also be considered in order to calculate Firing Strength. To determine the User Strength Factor, use the following formula:

User Strength Factor = (Character Strength)^2 / (Load Strength x 10)

Compare the User Strength Factor on the table below:

User Strength Factor

Bow Users

Crossbow Users

Greater than 1.5

Firing Strength = Load Strength x 3; a natural 1-4 on attack rolls means the bow has been damaged

Cocking and readying the crossbow takes one Attack

1 to 1.5

Firing Strength = Load Strength x 2; a natural 1 on attack rolls means the bow has been damaged

Cocking and readying the crossbow takes one Move Action

0.75 up to 1

Firing Strength = Load Strength x 1.5

Cocking and readying the crossbow takes one Move Action

0.5 up to 0.75

Firing Strength = Load Strength; suffer an Attack Penalty of -1

Cocking and readying the crossbow takes one Move Action

0.4 up to 0.5

Firing Strength = Load Strength x 3/4; suffer an Attack Penalty of -3

Cocking and readying the crossbow takes one Attack Action

0.33 up to 0.4

You cannot use this bow effectively

Cocking and readying the crossbow takes one Full-Round Action

0.25 up to 0.4

You cannot use this bow effectively

Cocking and readying the crossbow takes two Full-Round Actions

Less than 0.25

You cannot use this bow effectively

Cocking and readying the crossbow takes four Full-Round Actions

Note that there is no Firing Strength listed for crossbows; this is because crossbows always use Firing Strength = Load Strength x 2.


So how far out do bows reach? There are a lot of factors that go into such, but the easiest way is to calculate the Range Increment based on the Firing Strength of the bow.

Range Increment = ((Firing Strength x 2) ^ 2) / 30

Of course, you’ll need to recalculate Firing Strength – and therefore Range Increment and Damage – each time a character gains a new bow.


Determine the Damage Code of the arrows fired based upon the Firing Strength, as follows:

Damage Code = square root of (Firing Strength x 2)

Bows and crossbows are Piercing weapons, but do not gain the damage bonus for such; or rather, the damage bonus is already worked into the Damage Code above. They do, however, gain the Critical Hit values for Thrust/Piercing weapons.

Yet More Examples

So the Armourer has crafted a bow, four foot long and made of wood, and a crossbow, with two foot staves and made of wood.

The bow has a Load Strength of 12, and weighs 3.2 pounds (rounded down to 3). Therefore, its Wield Strength, as a single-hand weapon, is (3 x 4), or 12.

Aleveras picks up this bow, and attempts to fire it. Luckily, the bow’s Wield Strength is not over half again Aleveras’ Strength, so he will suffer no penalties due to the unwieldiness of the bow. His User Strength Factor will be (9 x 9) / (12 x 10), or 0.675. According to the table, Aleveras will have an Attack Penalty of -1 when firing this bow, and his Firing Strength will be 12. His Range Increment will be ((12 x 2) ^ 2) / 30, or 19.2 feet, rounded down to 19. His damage will be equal to the square root of (12 x 2), or 4.90, rounded down to 4. Or, in other words, a damage of 1d8.

Now Druul picks up the same bow, and attempts to fire it. His User Strength Factor will be (17 x 17) / (12 x 10), or 2.4. According to the table, his Firing Strength will be (3 x 12), or 36! But should he roll a natural 1-4, he will snap the bow like a twig. Druul’s Range Increment will be ((36 x 2) ^ 2) / 30, or a whopping 172 feet! His damage will be the square root of (36 x 2), or 8.49, rounded down to 8. That’s a base damage of 2d6. But the relative fragility of the bow means he should probably invest in a larger, stronger bow.

The Crossbow has a Load Strength of 12, as well, and weighs just as much. It is overall more compact, however. Its Wield Strength, as a two-hand wide-grip weapon, is (3 x 4) / 2, or 6.

If Aleveras attempts to use the bow, he will have no difficulties due to its weight. His User Strength Factor will be the same as for the arm bow, but according to the table, this means he need merely take a Move Action to reload the bow. His Firing Strength will be double the Load Strength of the bow, or 24. So his Range Increment will be ((24 x 2) ^ 2) / 30, or 76.8 feet, rounded down to 76 feet. His damage will be equal to the square root of (24 x 2), or 6.93, rounded down to 6. This is a damage of 1d10.

If Druul uses the crossbow, he will have exactly the same Range Increment and damage. Why? Because the bow is wound to a Firing Strength of 24, no matter who uses it! The difference is that, with a User Strength Factor of (17 ^ 2) / (12 x 10), or 2.4, Druul can jack that crossbow back into battery with a single attack. If Druul gets multiple attacks in a round, this means he could potentially deliver more than one crossbow shot per combat round – a significant advantage.


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