There are different moves in self defense. You can use these moves to defend yourself. When you watch this, sometimes it seems that's not so powerful. It's just a slap. It does not do much to the attacker.
Well, every move is not designed to make the damage. There are some moves that you use to distract your attackers with a view to making your next move.
So don't judge it seeing from outside. It works in different situations based on the context. Let's watch this video. You will see different self defense moves in the video.
Please feel free to let me know your thoughts in the comment section. Thank you.