Plus Three Versus
Magic weapons carry the legacy of the wielder.
To make a weapon +1 versus a specific type, kill one hundred of them with that weapon. Give the weapon a name.
To make a weapon +2 versus a specific type, kill two hundred of them with that weapon.
To make a weapon +3 versus a specific type, kill three hundred of them with that weapon.
No estimation is permitted. The count must be exact.
Weapons with specialist manufacture (e.g. forged by the extinct giants, quenched in venom) may halve these requirements.
To make a weapon +1 versus all types, kill a thousand with that weapon.