The following is Open Game Content from a 3PP Source
Aura strong abjuration; CL 13th
Slot none; Price 62,950 gp; Weight 4 lbs.
Witch-killer is a +2 longsword that is especially dangerous to witches. When used against a witch (and only a witch — all other spellcasters are not affected) the sword has a +4 bonus to attack and damage and deals another 1d6 damage. In addition, the sword also drains spell energy from a witch, preventing her from casting spells. Each time the witch is hit by witch-killer she loses one available spell slot, beginning with the highest level spell slot she has. If the witch has no available spell slots when she is struck by the sword she instead loses the use of a tradition power, beginning with the most powerful tradition power she currently has.
Requirements Craft Magic Arms and Armor, spell turning; Cost 31,950 gp