Lea will be the one to strike the necessary final blow, because he won't want the others- who (sans Sentinel) he considers better people than himself- to have to do it.

He'll as the little girl for her name, though, before he does it. Both so he can remember her... and so he can say who it was for when he kills Galos. (Not that he'll be able to due to how things play out, but he'll very much plan to.)

Also he and Elsa will end up having an argument after the fight ends, though I'd have to confer with her mun before I can say how public it was, and thus if any other chars know about it.