We are not dealing with just any librarian, but with Achille Ratti, who became Pope with the name Pius XI.
And the gun?
Here’s the explanation of this oddity. When he was prefect of the Ambrosian Library in Milan, Ratti kept a a revolver close at had "as a deterent to keep off possible miscreants with gunshots in the air, or the like."
Once promoted to the Vatican Library, he brought his gun with him. And when in 1918 Benedict XV sent him to Poland as an apostolic visitor, he sent to Warsaw via the diplomatic pouch, "a small revolver and ammunition".
As Pope, we don’t know. But it occurs that he could have been a quick-draw, based on the motto he chose for his episcopal caot-of arms: "Raptim transit" , "it goes by swiftly", a citation of Job 6:15.
When I read it I thought immediately of Spaghetti Westerns. Instead of Clint Eastwood, maybe Pope Pius XI could have starred, or maybe co-starred with St Gabriel Possenti.
I thought up a few titles, but please by all means add more in the combox:
For a Few Prayers to St Thomas More
The Good, the Bad, and the Holy
Fistful of Rosaries
Once Upon a Time in the Roman Empire
and there's one title that would fit perfectly: