Well, Mithias does have a breastplate on. A human can't cut through metal. ^^; Oh, and Mithais is also grappling Hank from behind and is too strong to wrestle. Hank is kinda pinned. I'll let you change your post.

As far as killing, you can kill Mithias by:
blowing him up, 
impaling his heart,
cutting off his head,
burning him to a cinder,
damaging him so much he can't defend himself, and one of the above.

Mithias himself has no weakness to silver, but he does to anything holy.

How do you feel about being turned?