Options for use-of-force & non-lethal weapons...
There are a few situations that could warrant using a Taser or OC spray BUT you(as a private citizen) need to be fully aware of how you'll defend your actions later.
With a knife, impact weapon(PR24, ASP etc) or other system YOU may be considered the aggressor by the responding LE officers or the media.
Street people, junkies, etc can and do show up at events all the time. You may look like a victim but that could quickly turn very ugly.
I'd add that to avoid conflicts or events that could lead to a dispute is the best step. Panhandlers or street people have nothing to gain or lose by being arrested. They get off the streets for a few days or weeks.
Is a fight or use-of-force incident really worth it?