It looks like a pizza cutter attached to a pistol grip...
As this is probably inspired by the Assassin prestige class (which is illustrated by an half-orc in the core rulebook), I'd say it is a crossbow.
I can see how the angle of it in the picture makes it look like a pizza cutter, but it's an xbow. :)
MUST....HAVE...IT! I just found my new player character! Of course it's difficult to sell an assassin as a protagonist, so I'm invisioning a masked vigilant fighting crime in the dark alleys of Absalom! (feel free to steal that idea) Now I need the Complete Character Folio! lol