+1 on pepper spray with a Krav Maga class. I've been blasted and it was pretty difficult to see or breath, which pretty much took me out of the fight.

And though I'm a fan of concealed carry, my G23 is not the right tool for scaring off tweakers who don't have murderous intent. You don't want to be the guy who is waving a pistol without scaring anyone...NOW WHAT? if you DOn't' shoot, you risk getting the gun pulled from you along with all the rest of the stuff they were gonna take in the first place...
Any ol' tweaker-be-good stick (16" of 5/8" rebar) will work.

Of course if they pull first, then the ONLY way to protect yourself is with your sidearm.

Has anyone been murdered by "tweakers" on the Sky?
An old lady gettin' murdered by a kid with an itchy trigger finger doesn't count, and I doubt he was tweakin'...did anybody drug test that kid?