Warbringer

This massive, wickedly curved red-bladed sword is a +3 keen vicious falchion that murmurs a low, rumbling battle chant when drawn. Whenever the wielder confirms a critical hit with a warbringer, the wielder gains the benefits of rage for 1 round (if a barbarian, the wielder gains 1 additional round of rage for that day), while the creature struck is compelled to move toward and attack its nearest ally with a melee weapon, natural weapon, or unarmed strike on its next turn (DC 14 Will negates), as the murderous command spell.