Just thought of this: try dismissing him from the party, right-clicking on him, then adding him back to the party again. Never tried that in the game, but it should work.
As Pyrates mentioned, he definitely can go insane. In one battle he ran amok and almost obliterated my poor little fairy monk before I restored his sanity.
But all in all, I liked having him in the party. No magic, but a very effective fighter. And I liked a lot of his comments.