I don't think that one could "break leather" to defend themselves against being sprayed with mace. Typically, it' fear of death or great bodily harm. That said, if one was allergic to mace.......
If I knew it was mace, I'd hold fire. But if someone gets into an argument with me, then says something along the lines of "I'll teach you!" and reaches into their purse/bag/pocket, then it's "go time".
That said, there doesn't seem to be many details on this... I'd like to see more information.