Weapons aren't an option here in the UK. I am acutely aware of the type of people around me depending on where I am. Flying in open spaces near cities, you'll usually come across someone who might be interested in your Phantom for the wrong reasons. I do have a plan, though:
If I'm flying in a risky area, I'll take off near my car. If the wrong type approach me, I'll whack my Phantom high up, get in my car with the RC, drive to a safer place, and pilot the Phantom to me. How well that would work, I am unsure. But, at least I'd still have my wallet, phone, and RC if I was unable to fly the Phantom to me.
Lets hope I never have to do that, though.
Sit in the car for a minute and if they harass you, use the phantom to get a good photo of them from 20 feet up before driving off.