I say you handled the situation calmly and effectively used what you had with the right application. Sometimes it's just a matter of communicating your intent without "brandishing" to let others know that you're not a pushover.
In Phoenix, that kinda stuff is VERY common. There's a ton of carjackings where the perp just jumps into the car, physically pulls or pushes out the driver and they got a brand new car! I've even had a few try to steal a motorbike out right from under me. Of course, criminals are stupid and don't realize most bikes are about 3x faster than cars and most bikers are ALOT more observant (Did alot of impromptu sidewalk driving in South Phoenix along Van Buren between 7th street and 48th street).
Don't have auto-locks in the tracker, but always drive with the doors locked at all times. Not really paranoid of that kinda stuff, but it's really just a hangover from my days driving a cab for years. Part for security and part because when you're a cab driver, sometimes you just don't want to take a fare no matter who it is because, well...you need a frickin' break! Even had one drunk guy jump into my car when I was eating lunch in front of a taco stand and get all pissed off when I pointed out my "off duty" light. he said "F*** you man! You're SUPPOSED to drive me where I want!".
I just threw a hot sauce packet againts the cop car parked next to me to get him out. Now he had an irritated cab driver AND an irritated pair of cops jumping on his case because he interrupted both our lunches.