SRD:Vicious

Vicious: When a vicious weapon strikes an opponent, it creates a flash of disruptive energy that resonates between the opponent and the wielder. This energy deals an extra 2d6 points of damage to the opponent and 1d6 points of damage to the wielder. Only melee weapons can be vicious.

Moderate necromancy; CL 9th; Craft Magical Arms and Armor, enervation; Price +1 bonus.