I absolutely agree with the lawsuit idea but not with the knife. Oftentimes if the person with the knife isn't trained enough it could be taken and used against them. Not only that, but if you stab someone it won't necessarily stop them. They will immediately go into shock and probably not even know they've been stabbed. And, in the worst case scenario, they might kill somebody and go down for murder or manslaughter despite originally being the victim.

I recommend a tactical whip or a monkey's fist as opposed to a lethal weapon.