Taser/Stun Guns
Taser guns can be used to disable an attacker and calm the situation, although a lot of the taser guns have the big disadvantage of only 1 shot , some of the taser guns have 3 to a maximum of 6 rounds. There is also a taser shotgun out there.
Kubatons/Batons
Kubatons can be a concealed weapon that you can defend yourself with, it is very effective when coming to it`s technique. On the other hand Batons cannot be concealed because they are a little too big. Batons are used by police forces aswell.
Pepper Spray
Not much to say about the pepper spray. In my opinion it is very unreliable because of the simple reason that if you don`t hit the eyes or any where near you`re never gonna actually stop an aggressive attacker.