I don't know man, him being the omnipotent berserk that he is, I would like to know just what exactly it took to stop him. Then again, it was probably something insignificantly simple.
Holy crap, I knew that Azrael did something to Rachel since I saw his translated arcade mode play-through but I didn't know that he might have acquired vampire powers while he was at it.
Wasn't it implied that Ragna is an artificial human or something? I wonder if Azrael knows just who and what Ragna is exactly.
I guess he's his own kind of villain. He's not out to conquer/destroy the world like the others but fighting and killing people for the helluvit, specially when it just so happens that all of the "good guys" are well-known, powerful individuals, doesn't exactly make him neutral either. You kill the good guys for the lulz and to test yourself, and you're no longer a neutral force, I suppose.