A civilian improvisation refined by real-world outcomes: the 'keys between the fingers' punch tends to injure the defender more than the attacker. A thrown key ring buys the same distraction with none of the downside.
Use a key ring to buy the beat you need to escape, not as a fist-pack weapon.
Forget the movie image of keys woven between the fingers. Struck against a jaw or skull, they slice the defender's hand and rarely stop an attacker.
Instead, hold the ring loose and throw it at their face. The eyes track motion involuntarily; a jangling metal object flying at the head steals a full second of attention.
That second is the technique. As the keys leave your hand, your feet are already moving - to your car, to a barrier, to distance. The keys were the decoy; escape was the goal all along.