I'm agreeing with Sadrith on this. You can't compare real life weapons and skills with that of a fictional character like X-men or whatever. It's fiction for a reason.
As for me, I'd prefer to use a gun. Guns are by far more harmful and accurate. When you're talking blades you mean a sword, not a knife. A sword really does take skill to use properly and efficiently, whereas a mere child can handle a gun and kill someone with it without knowing anything about how to use it.