One other thing: I've mentioned in other threads that pepper spray is an inferior self defense mechanism, so I hope you'll forgo that as your preferred weapon. It's just too unreliable and difficult to use, particularly under duress. I am genuinely concerned about the false confidence carrying pepper spray gives to people, thinking they are protected, when they are not. Stick with a blunt force weapon like the kubotan, that you can take anywhere, and requires only hitting the person with all your might to be effective (especially if you hit them in the head, face, groin, lower arms, or hands).
Pepper spray requires you to get it out, properly orient in your hand, release the safety mechanism or cover, accurately aim, and depress the small button with your finger. This takes time, and it requires fine motor movements which are all but guaranteed to fail under duress. Even if you succeed in deploying it, you need to hit the person in the face with it, and hope that it works (some people aren't terribly phased by it, or are at least able to fight through it). Also, the way it is held, pointing out in front of you, makes it relatively easy for an attacker to take it away from you and then use it against you.