I forgot that Matsu had this ability (from his Sadist Archetype):
Exquisite Agony (Su)
When a member of the sadist's collective dies, instead of needing to make a save to avoid taking damage, the sadist gains a number of temporary power points equal to the Hit Die of the creature killed. These power points last a number of rounds equal to the sadist's Wisdom modifier and do not stack with each other or other temporary power points.
This would have saved him a few power points on that last Vigor he used. How many HD did those arm things have, anyway?