The pit is outside of the room, in front of the stairwell. Getting him back there would take some work. You can grapple him where you are, try to get by him, dagger, punch, etc. I'm not a big fan of the unarmed combat rules. I'll have to look them up. Or just roll to hit, then its Str. check to hold, Str. check to break free, that sort of thing.

