Bane Weapon

This spell makes a weapon more potent against a particular type of creature. Against its designated foe, the weapon's effective enhancement bonus is +2 better than its normal enhancement bonus. Further, it deals +2d6 points of bonus damage against the foe.
Range: Close (25 ft. + 5 ft./2 levels)
Clr 4, Sor 4, Wiz 4

From: Dragon #279