Killed him.
And a hell of a fight it was. When he was in his regular mode, he was pretty easy, but in Frenzy mode he became quite a bastard.
The turning point came in a ridiculously epic moment that almost looked scripted; he was charging right at me, I jumped off a ledge to meet him, by blow connected first, toppled him.
See this is the kind of thing most games today lack; the ability to do epic stuff like this without it being a cutscene or scripted QTE.