Kubotan - original

Kubotan is a genericized trademark for a self-defense keychain weapon developed by Sōke Takayuki Kubota in the late 1960s

Applied as a weapon, some of its usage can be similar to that of the yawara stick or koppo stick. The principal
targets in self-defence include bony, fleshy and sensitive parts such as knuckles, forearms, the bridge of the nose, shins, stomach, solar plexus, spine, temple, ribs, groin, neck and eyes. The Kubotan is usually held in either an icepick grip (for hammerfist strikes) or forward grip (for stabbing, pressure point attacks and seizing). Common uses include hardening the fist (fistload) for punching, attacking vulnerable parts of an assailant's body, and gaining leverage on an assailant's wrist, fingers and joints. With keys attached, it can function as a flailing weapon. As a pressure point weapon it can attack any point a finger can, but with greater penetration because of the smaller surface area at the ends.