Thanks, guys.
The game is Midnight, by the way. This might mean something, or might not.
Due to a houserule of mine, I allow any skill barring spellcraft and certain knowledge skills to be class skills. I say that character skill points are limiting enough. He puts all his ranks in Jump, Climb and Move Silently.
As for different styles - I do. I'm a vaguely experienced GM, and I try very hard to have everyone have their special moment.
Auld Grump, I might well have to change the DR rules to what things should be. However, this would in the end make him just as tough in another way; now, instead of doing little damage, he simply wouldn't be hit at all. I'm uncertain whether that is the correct solution.
Anyway, I've played another session and things have calmed down a bit from the first 5 sessions. He's still Mr. Unstoppable, but at least he doesn't manage to steal the others special scenes. The change of character from another PC admittedly helped somewhat, (And none of my urging) but it struck me as horrible that a player would change his PC so he could actually get some attention as opposed to being second fiddle.
Thanks again. Now the opposite will be in effect; the previously nigh-useless character will kick major arse and our big, bulky fighter with his criticals will not do a lot.. unarmed.