well on a computer game I develop my characters have some great weapons...how about a bow which fires arrows that are super hot and combust on impact? or a longsword with an icy cold blade that can cut through steel as if it were a hot knife in butter...or my Personal favourite:

Mercy, a sai which after being used to stab the opponent freezes the flesh surrounding the immediate stab wound an electrical discharge is then emitted shattering the frozen flesh freeing the weapon again and to stop the wielder getting frost bite from wielding it for excessive time they must wear gloves made of demon skin.