Ideally it would be a knuckle, but that's just like... my fist. Even if it does cool stuff like make my entire frame glow or connect after my arm extends infinitely, it's still just a punch, you know? Mouth beam is still a beam in my head, not a piece of equipment.

So it'd be a Colt Python. You know, I'm this advanced piece of machinery with enough horse power to fold you in half with my bare hands but the most efficient manner of combat is just an old fashioned double action revolver with high caliber ammunition. It works for Terminators.