Thats pretty wild looking, the dots on its back. Sorry, not that great at IDing though. Be careful, it has thin pinchers.. im sure you know the rule of thumb (small pinchers, possibly high toxisity). Good luck.. hope someone can ID it, i want to know what it is also.
I don't know its exact venom potency. Based on its genus, however, I'd say it won't kill you but likely produces a VERY painful sting.
Now, it may be on the lower end of the scale for its genus, but until you actualy know that, I'd assume it is as bad as Mesobuthus comes and play it on the safe side.
EDIT: Oh, and as for ID, I am almost possitive it is a Mesobuthus. I am also pretty sure about the species, though some extra pics can't hurt. You can send them to firstname.lastname@example.org if you'd like.