Also, batteries are a huge limiting factor too. Life is very good at storing energy, but a bee travels about 5 miles a day. In the example of the attack on college students, I think the perpetrators would have to be pretty near to the college (unless it's a very expensive assassination campaign).

These hurdles might be overcome with additional 'feeder bots' that charge the warriors. But, still, that's becoming more complex.

But the question for assassination cases becomes--why bother, when low-tech choices can do the trick? How about hiring thugs to take out your targets over time, to be less suspicious? You could vary the methods to include things like poisoning. And don't tell me that paying the thugs is too risky--this company was already considering buying assassin drones.

I think when it comes down to it, the horror of things like war and assassination are simply that we kill people. I'm not sure if being pacifist is too political for this sub, but for example, when I hear about people being killed in Syria by drone strikes or by being shot by soldiers, the drone part isn't particularly horrible, it's the killing part that is.

The thing is they would be fighting each other... the war of the future will be robots vs robots, but the robots will be in a wide variety of shapes and sizes.