[Ejidoth]

It will generally require implausible materials for weapons since you're increasing the density by quite a lot, but in general, as long as you're changing just the material and not the size or shape of the weapon, you can power it up like so:

1. Multiply its MinST by some number, I'll refer to it as X.
2. Multiply its actual weight by X squared.
3. Multiply any damage modifiers it has by X.

This looks counterintuitive at first glance, because some weapons have zero or negative bonus, and multiplying those seems to make the weapon heavier for no benefit or even appears to make it worse.

Remember that triple a melee weapon's MinST is the maximum ST you can use with it, so even in cases where the bonuses aren't impressive, heavier weapons let you use higher ST.

A hatchet does swing cutting damage, no bonus. It weighs 2 lbs. and has a Min ST of 8. If your ST is more than 24, you can only use 24 of your ST safely to attack with the hatchet.

If you make a hatchet out of some super crazy dense material so its Min ST is 80, it only does swing cutting damage, because you're multiplying a damage bonus of +0 by 10, which still leaves it at +0. You now have a hatchet that weighs 200 lbs, requires 80 ST to use effectively, but lets a super with 240 ST use his full strength to do some serious swing/cutting damage.


The main reason these rules don't work well for scaling weapons to large and small characters is that it doesn't really account for stuff like changing the size of a thrusting weapon's wound channel, or how long it takes to attack with a swing weapon and what affect a longer or shorter lever arm should have on the damage. But if you're just changing mass without actually scaling the weapon any differently, multiplying's fine.

EDIT: Technically, if you want something that's more physically accurate, step 3 is a little more complex. Weapon damage should really scale with the cube root of its weight (i.e. with its HP), not with the square root of its weight (i.e. the ST required to use it.) But the math gets weird there, and doing it the way I outlined above is balanced enough since it lets appropriately-massed weapons provide proportionate benefit to any ST.