I always thought a paintball gun would be a handy tool to carry in situations like that. It is non lethal. It is legal. And it hurts like hell to get hit in the face with one.
Of course if that is not enough you would have to resort to a more lethal tool.
You mean like lead paint?
If loaded with pepperballs it becomes more effective. Unfortunately, Antifa is often seen wearing facial protection so it would be less than effective.