"Firstly I'd be wondering if they have dangerous magic, why would they be using a gun? Anyway, I'd approach, carefully, and tell them that this is neutral territory and that neither they nor the threatened patron is allowed to use violence here. Since I'm not a magic user I'd also be looking to see if there was any available magical backup. I'd tell them that I am a member of the security team here. If none of this was successful, I'd ask the threatened patron if there were any others from their world who could explain what was going on. And if all else failed, I'd get the crossbow trained on the new patron and tell them to drop the gun. If they don't know the rules they don't know I won't shoot them."
no subject
"Firstly I'd be wondering if they have dangerous magic, why would they be using a gun? Anyway, I'd approach, carefully, and tell them that this is neutral territory and that neither they nor the threatened patron is allowed to use violence here. Since I'm not a magic user I'd also be looking to see if there was any available magical backup. I'd tell them that I am a member of the security team here.
If none of this was successful, I'd ask the threatened patron if there were any others from their world who could explain what was going on. And if all else failed, I'd get the crossbow trained on the new patron and tell them to drop the gun. If they don't know the rules they don't know I won't shoot them."