Oh! Sorry I didn't mean the use of lethal weapons to kill the attacker xD, I meant just using a blunt object or something similar to subdue the assailant. I also got your point about the weapon being able to be used by both parties, but odds are if the person was truly serious about assaulting you, they'd most likely bring a weapon of their own, in which case the use of a spray would be a surprise and take the attacker of guard to let you have a chance to escape and get help.