A knife as a self-defense tool is not bad. But you are going to have more success with this gun knife. The Arsenal Gun Knife can fire .22 caliber rounds. It goes without saying that these types of knives are rare. They are like a regular knife but you can reload them for a gun fight by pulling up the trigger. The barrel holds 6 bullets. Unless you are taking on an army, this should be enough as a self-defense tool.