Nope, you can't take a generic Chapter Master / Grandmaster in 4th like you could in 2nd, 3rd and 3.5. Apparently the Chapter Masters of all the Unforgiven Chapters now have the Sword of Secrets, Lion Helm and Watcher in the Dark. There must be a forge somewhere pumping them out.
Azrael has his uses, but he's definitely not for everyone. I agree with the suggestion that a generic Company Master would be a good choice. He's not as killy as a Chapter Master, but he's still decent and pretty cheap too boot.