As someone who once worked as a Manager in the Private Security business, let me say this. They do not care about you. You can't be trusted with a gun. You are a liablity to them when you have a gun. They would rather you die, than be sued by someone you shot. They have yuppie lawyers in this industry that are not only anti-gun, but don't have a clue about shootings in self defense. Further, they don't want to waste the money on you for training you with a firearm. Even if it cost only $100, as was the case in the company I worked for, it's still a waste to the bottom line.
If your widow sues because you were not allowed to be armed, they will say the customer didn't want armed people, or that you knew that you were going to be unarmed anyway. They would rather fight a lawsuit by you or your family, than a lawsuit brought on by a perpetrator or his family. I'm telling you the absolute truth here. In a national company, the people who generally make decisions about you being armed are are sitting behind a big desk in New York, looking at the bottom line and figuring the liability risk. That's it. We used to get memos telling us to discourage customers from requesting an Armed Guard. If they demand it, we should charge them heavily for the service of being armed, to counter the cost of liability and continue to discourage the customer about guns. Any weapon to them is a liability and a threat to their profits. Even Pepper Spray and batons. Nothing more. One Manager I knew was so concerned about the liability to his bottom line interfering with his quarterly bonuses, he made his armed guards keep the gun unloaded and ammo in their pocket like Barney Fife. He said, if trouble started, they could load their revolver, but only with 5 rounds, not 6. They charge the customer $16 and hour, pay you $8 an hour, and use the rest to pay for your "used" uniforms, their own liability insurance coverage, Supervisors having to drive by and check on you, etc.
I got out of this business because it is such a cut-throat industry. If your company gets a contract, someone from another company is already approaching that customer for doing it for a nickel per hour less. That is why there are so many minimum wage, sloppy, or Goofy Security Guards out there. There are some highly paid profesionals in Security with Law Enforcement experience and college degrees, but the contract guard service is generally a joke.
So just to let you know, the risk is on you and you alone. My personal decision would be to have a concealed 38 Airweight or a good .380 in a pocket holster or something. Nut you will be fired and they will try to distance themselves from you legally if you have to shoot. Your call!!!