Over- and undersized weapons are a popular trope for fantasy and fantasy-adjacent stories. Those giants and pixies need something to fight with, and human-scale warriors with huge swords is a itself a popular genre trope.

GURPS already has a pretty good set of cinematic rules for representing these. The best source of these is the Scaling Weapons and Armor section found in GURPS Low-Tech Companion 2: Weapons and Warriors. GURPS Dungeon Fantasy uses a limited subset of those in DF1 and 3.

However, there are a few other tropes that mess around with weapon weights in a supernatural way. Let’s take a look at how to represent them in GURPS.

Superheavy Weapons

This is a melee weapon that’s the same size as its mundane counterpart, but it’s a lot heavier. It’s probably made out of a non-standard material, which depending on the weapon might be a fruit of superscience or magic. Such weapons are usually built for legendarily strong wielders! The increased weight not only makes the weapons more deadly, but also allows its owner to employ their full strength when fighting.

To model these weapons, use the Scaling Weapons and Armor rules, with a few modifications:

  • Either pick a final weight for the weapon, or note the strength of its intended wielder if you already know that.

  • Go to page 21 of Low-Tech Companion 2, and pick the line whose “Typical User ST” column most closely matches that of the wielder.

  • If you started with the weight, divide final weight by the “base” weight of the weapon and pick the line whose Weight column is closest to the result.

  • Modify the weapon’s Damage, required ST, Weight and base cost as written in LTC2. Do not modify Reach or SM.

And there you have it! And yes, you can combine this with normal weapon scaling to make a weapon whose weight is abnormally large for its size. In that case, two extra steps apply after completing the procedure above:

  • Multiply the weapon’s Reach by the value in the table row corresponding to the SM of the intended wielder.

  • Cost is the higher of the weapon’s final modified cost, or the cost of a standard SM 0 weapon.

Example 1: We’re making a super-strong martial artist character and we want him to use an iron quarterstaff that’s ten times heavier than the wooden variety. Looking at the table on LTC2 p. 21, we see that the closest multiplier is 12.25, for the SM+3 line.

After applying the modified process above, we end up with a weapon that has the following qualities: Damage sw+7 cr or thr+7 cr; Reach 1, 2; Parry +2; Cost $122,50; Weight 20kg (40 lbs); ST 25. So our hero would need at least ST 25 to properly wield such a weapon.

Example 2: We’re making a pixie barbarian using Dungeon Fantasy rules. Her ST is 13, which is legendary for a people whose SM is -6 and whose typical ST score is 5. We want her to wield a weapon that’s superheavy for a pixie.

The chosen base weapon is a Dueling Halberd. We use the SM -6 row in the table for the halberd’s Reach multiplier, and the SM -2 row for everything else. Our resulting halberd will weight only a quarter of the human version, but it will be 25 times heavier than a “standard” pixie polearm, and weight more than its wielder! Since its modified cost of $30 is lower than its base cost of $150, it costs the same as a full-sized halberd.

The final stats are: Damage sw+2 cut or sw+2 imp or thr+2 imp; Reach C; Parry 0U or 0; Cost $150; Weight 1.25kg (2.5 lbs); ST 6++. Note that our super-strong pixie can wield this halberd one-handed without it becoming unready.

Magically Attuned Weapons

This trope is popular in the Exalted roleplaying game. Magic weapons in that setting are based both on some tales of classical mythology and on modern media such as action anime and certain video games. The heroes who wield these weapons “attune their essence” to them, which makes the weapons feel like they have normal weight to their owners, while still being superheavy to everyone else - particularly their targets.

This means that characters wielding these weapons don’t have to be generically super-strong, and that the ability to handle one weapon doesn’t give them the ability to wield others.

To create such a weapon, use the same process outlined above for “superheavy” weapons. Attunement is represented by a new advantage, which the weapon’s owner must purchase in order to use it.

Attunement (Variable Cost)

You’re attuned to a specific magical weapon which is super-heavy, oversized, or both. You can wield it just as if it was a normal-sized weapon, though its targets will still feel the full weight of your blows.

To calculate the cost of this advantage, subtract your actual ST from the weapon’s minimum ST and multiply it by 1.6, rounding up. Add 1 to the total if the weapon is also oversized.

Attunement in no way “protects” your weapon! If it’s permanently lost or destroyed, you lose all the points invested in it.

Details: This is just enough levels of Lifting and Striking ST with the limitation “Only for this weapon” (-80%) to cover the difference between the character’s ST score and the minimum ST for the weapon. The extra point for oversized weapons is a specialized version of the Giant Weapons perk that removes all penalties due to size difference, but only works for that single weapon.

Example: If the Iron Staff from the previous section was a magic artifact in the style described here, a reedy ST 8 hero could attune to it by paying 28 character points. 25 - 8 is 17, which multiplied by 1,6 gives us 27,5, which is then rounded up. This allows the hero to fight with the Staff as if he had ST 25, and to ignore its great weight when carrying it, but he’ll still be ST 8 for all other purposes.

“Whomsoever wields this hammer, should he be worthy…”

The third and final special weapon covered in this article are those powerful magical artifacts that only allow those they deem worthy to even lift them. Thor’s hammer from the Marvel comics and movies is a famous example.

Lifting and using these weapons is not a matter of muscle mass, but of moral strength. When you touch them, they judge you! If you pass that judgment, then you can lift and wield the weapon as if it was a normal specimen of its kind.

You don’t actually need to make these weapons superheavy or oversized. Instead, they look for certain traits in a prospective wielder. Those who have these traits are worthy. Those who don’t can’t even lift the weapon, even if they’re the strongest being in the universe muscle-wise. I generally consider this to be a story effect and wouldn’t try to put a price tag on it.

A weapon like movie-Mjolnir might look for one or more virtues along the lines of Honesty, Selfless, Charitable and so on. An evil weapon would instead look for Bloodlust or Sadism. They would of course also avoid traits opposite to those they like.

If the weapon in question is also superheavy or oversized, then it could grant worthy wielders the ST to use it, similar to how Attunement works, at no cost to the wielder. If you’re writing up the weapon as a character, this would be a benefficial Affliction granting the Attunement advantage described in the previous section of this article. Simplify its cost by having it grant a number of levels of ST equal to the minimum needed to wield the weapon regardless of the wielder’s current ST.

Example: The Iron Staff belonged to the Monkey King! Though it will shun Bloodthirsty, Callous, Greedy or Sadistic individuals, it will deem worthy anyone who shows its former master’s heroic spirit, martial prowess, or love of mischief. Anyone with at least two of Selfless, a Code of Honor or Higher Purpose to fight evil, Trained by a Master, Curious, or Trickster could be deemed worthy and be considered to have ST 25 when wielding the staff.