The Sword of Lankor

Take one alien planet somewhere in the heart of the Milky Way, and very much like Earth.
Take one brawny barbarian adrift in the capital city of that world's largest Bronze Age empire.
Take one "miracle" in the form of a golden globe descending from outer space to announce a contest and a quest in the name of the country's chief idol.
Mix them up and what you get is a terrific science-fiction adventure of the Burroughs type. That's THE SWORD OF LANKOR.