You are in a crowded theater, Bat Man is about to start!!!
Just then, a guy bursts in the bottom door in a Ninja outfit, with a Samurai sword. Woops, but only a few people see. The door closes, fake punk Ninja gets busy, screaming begins.
Oh, he is Insane and has a short sword. (taught by his mother, now dead)
So, realistically, I think he would be able to kill many people, don't you? This is how it happens world wide. Mass murder is based on the culture. With no guns around, like Japan, Bladed weapons are murder in a crowd.
We have the 2nd, so we mass murder with guns. Tampering with us about this can only lead to bombs, blades, Saran gas, etc. It must just be a logical conclusion to certain folks.
It then only matters, what is the weapon of choice? I think more people fear the blade, actually.