two words: PEPPER SPRAY

Great for self defense, you spray it and run. I've never heard of anyone being charged for using pepper spray in a confrontation. The reason is simple- there is no way you can purposefully kill or assault someone with pepper spray, therefore there is no INTENT. Other weapons like knives, canes etc. can all be purposefully used to inflict disproportional damage, and can open you to charges if you are ont careful.

That is why I will always stand by good ol' pepper spray.