I have a couple of Ka-bars, including my late cousin's issue piece. The only thing I don't like about them is the tip is a bit delicate, and easy to break. The cousin's knife was broken this way when I got it; I re-ground the tip to more of a spear point. Otherwise, Ka-bars are great.

However, as mentioned by Hobowh, knives are a last ditch tool for combat. If you're talking about a combat situation, I consider a pistol to be a tool used to acquire a rifle. Same with a knife.