The ultimate staves can take him out in one charged shot. Well, at least the fire one can which is the one I always use. I'm not sure about the others, but I would think they could as well. The regular staves are pretty good against him too. Other good weapons are the Ray Guns and the Pap'd Mauser. I've heard claymores are effective as well, but I haven't used them much on this map.
If you do happen to get grabbed you can shoot the arm that his claw was fired from to be immediately released. In-game quotes suggest that his arm is a weakspot, but the head is an easier target imo.