What is the best self defense weapon?

The best thing in my opinion would be to have a dog with you. My girlfriend always has her bulldog-labrador mix with her when she goes for a walk in the park in the late evenings. She said she was once approached by a group of dangerous looking youngsters but when they saw the dog on the lead they immediately backed off.

In your case a dog might not be so practical at school. Apart from this "dog option" I think pepperspray is still a good deterent if you practice how to use it first because it does disable someone pretty quick and in most cases doesn't do serious injuries. Another option would be a taser gun but I'm not sure if they are available for private purchase.

What I would not recommend is a knife or something similar because drawing a knife is more likely to provoke a potential attacker.

I would say a clear and active mind that can think under pressure, is your best weapon. that's its always advised one should always perform their techniques in training as its a matter of live and death. this is what such training is preparing you for.

No weapon will help, without the training to use it. Good training in traditional, empty hand combat is my choice. You always have your hands with you, so you are always ready.

Pepper spray.

A sound mind ( especially one that can think under pressure.)

gun....defitnately....