So often in these plays, there seems to be no superfluous language – no sentence that doesn’t pack in meaning or purpose. This one, though – feels almost like it’s here just for rhythm. I doubt there’s a real NEED for the “come on.” Except maybe, maybe – to project an air of enthusiasm about this whole duel – an enthusiasm that, likely, Hamlet does not really feel. So – yes, I’ve talked myself into the importance of this line after all. It’s not just rhythm – it’s a projection of confidence and manufactured enthusiasm.