Azrael is basically Broly. He doesn't seem like the "major villain" type since he has no grand plans. Just go around and blow shit up. I guess that could be a whole plot arc, but it's more likely that the cast will be busy dealing with Terumi, then AZRAEL OUT OF NOWHERE to throw everybody's plans down the toilet.
I would definitely put him as a villain though. Just the brutish unsophisticated type.
If you don't care about human life and just do whatever you want no matter the harm it causes, then that's a villain.