The way I have handled this is in the past for Melee weapons was a "coating" over any existing blade.
So, if they were going up against something allergic to silver, the melee adept could literally "buy" a Silvered melee weapon. (like a cougar fine blade, coating in silver.)
my argument is: if a few dozen grams of sliver/garlic/wood in a bullet is going to trip the allergy, then a whole blade slicing through the flesh and wound is going to hurt too!
As for price:
Material x 10 small objects (knuckles, knives, daggers)
Material x 30 one-handed weapons (swords, clubs)
Material x 50 2 handed weapons (Katana, axes)