Where did you come up with that? “olice are an obvious exception universally accepted by societies where law and order prevail.” Not true. The British Isles and many other countries have very few armed police. It is only accepted there in extreme exceptions.
You also say, “Can you honestly see Pope Francis encouraging the laity to come to Mass armed?” Uh the police are laity. They are not ordained. The Swiss Guards are laity.
Also, I have no desire to “take a step back from the very specifically conservative American culture that permeates this thread.” I, for one of us, an proud to be an American, and proud of our Constitution, including the Second Amendment. I served in the military to defend it. Other countries do, and should envy us, even with our flaws. And the Catholic Church would be greatly diminished if it were not for the United States.,