Same applies to a gun. You can take someone down with a gun if you don't care much for your life, same as if that person was good with a knife. Arguably close-quarters gun use requires less training to be lethal, but man, I've seen rather low-key (not para/military!) people who, with a knife, are pretty much unapproachable without the approacher being dealt serious damage. Arguably, people might be more inclined to run after someone with a knife, but hey, that's only a psychological effect and has no source in reality: they can be taken out by a skilled knife-wielder just as if he/she had a gun.
I've seen a recording of an experiment done with zip ties with real human participants, and that's why I even bother to mention them. I'd say they are a diversion so big that it almost guarantees untouchability. Scenario: you run up to someone and in about 400ms they have a zip tie tightly wrapped around their neck. Then you move on to the next target, as long as they are 20-30ft away. Whoever was next to that first person who is now in the process of collapsing will help them first, they won't he chasing no assailant. In the right hands and circumstances a bunch of zip ties is almost a perfect weapon.