New business idea: Wearable that sends out a shockwave if the user gets attacked. The user could adjust its sensitivity, i.e. if they're attacked from a certain

New business idea: Wearable that sends out a shockwave if the user gets attacked. The user could adjust its sensitivity, i.e. if they're attacked from a certain angle or they're hit with a certain amount of force. I'm mostly kidding, but if you're attacked from an unsuspecting angle then no amount of armaments will protect you from that first punch.