I think the fact that the gun was invented is enough evidence to show that it is a superior killing instrument. There was afterall a purpose to it's invention. I don't see many Katana wielding Samurai lining up on Iraq's border. There are however a considerable number of carbine wielding soldiers.
Yeah the sword is a graceful weapon and those that know how to use one (can't quite see the need in modern society) are very dangerous. But quite simply, the ability to hurtle lumps of metal into someone's chest at a rate of 600 or so per minute is a far more effective way of killing someone.
BTW, many people are duped by Hollywood into thinking that being hit by a bullet would send you flying back off of your feet. It wouldn't.