This set of +1 keen claw blades is most effective when the wearer has multiple claw attacks per round. When making a full attack with claws, if the wielder hits the same target with this weapon and a different claw attack or set of claw blades, he deals an extra 1d4 damage plus 1-1/2 times his Strength bonus. The wearer can deal this extra damage no more than once per round. This counts as a rend attack and does not stack with other abilities that grant rend attacks.