Tools are what separate us from animals. A knife gives us claws to accompany those brains. It can also be used by someone bent on hurting us. Everybody knows how dangerous a knife used against us can be. Many seasoned warriors fear the knife more than most any other weapon. Highly concealable, it never runs out of bullets and we all have used them since childhood which gives every one of us a certain level of proficiency in their use. And they can be found in just about any home. Here is an interesting article I read about knife attacks.