I have referenced a self-defense book in the past and one idea that I really enjoyed is using your keys as a weapon. You want to grab your keys and scratch an opponent much like a jaguar’s paw across his face. You hold them firm enough in your hand so you can slash at your opponent.
This reminds me of the Chinese military philosophy, “every person a soldier and every thing a weapon.” I encourage the reader to look around and find common items that can be used to protect yourself.
If anything use your keys like a jaguar’s paw. Couple it with the eye of the tiger.
Application for fathers: work with your kids and find items around the house you could use against intruders: cans of soup, chairs, flashlights.