The title of Arms and the Man by George Bernard Shaw is based on the opening line of Virgil's Aeneid,
Arma virumque cano, Troiae qui primus ab oris Italiam, fato profugus
I sing of arms and a man who first, exiled by fate, [came] from the shores of Troy
This line begins a great epic telling of the heroic deeds of Aeneas, who fled after the fall of Troy in the Trojan war to found Rome.
The purpose of the title is to give us a different take on warfare. Captain Bluntschli is also fleeing after losing a battle, but rather than being a heroic character about to found a great empire, he is a rather pragmatic, bourgeois mercenary, who is quite happy to abandon warfare for running a hotel chain when he has the opportunity to do so. In his meeting with Raina, which parallels Aeneas' meeting with Dido, Bluntschli is more concerned with obtaining food and getting some sleep than with glory.
What this does is locate the play in a "mock epic" tradition, which evokes the grand and hyperbolic traditions of heroic epic only to satirize and deflate them.