Silver
Silver is a natural precious metal. It is very ductile and malleable, ideal for jewelry and silverware, but hardly suitable for weapons due to its cost and softness.
Properties against Beastfolk
It is said by some that silver was provided to mortals by the gods for use in fighting the beast races. Whatever its origin, the touch of silver burns all beastfolk and lycanthropes, as well as vampires. For this reason, monster hunters such as the Venatori always carry at least one silver weapon for use against such creatures.
Weaponry
As a weak metal, silver is entirely unconventional for use in weaponry. Its only use as a weapon is its properties against shifter-kin, particularly as it is one of the only things capable of truly killing a werewolf. However, smiths among men do not know how to heat forges hot enough to melt silver into a liquid state, thus the act of coating a steel or iron weapon in a layer of silver is a mystery to them. Any silver weapons that are created must be made from actual silver, making silver arrowheads one of the only remotely conventional weapons that are able to be crafted from the metal.
Rarity
Silver weapons are extremely rare and extremely expensive. A considerable amount of silver must be used to make any kind of silver weapon, making the price of such a thing tremendous. Additionally, due to such weapons being essentially useless outside of monster hunting - and most silver melee weapons being useless anyway, given the weakness of the metal - only a few blacksmiths are willing to try and work with silver at all, and they charge exorbitant prices.