Star Guard

When Earthmen got into space, they found advanced races who deemed Earth far too barbaric to join them. They were assigned the only task deemed suitable, mercenaries on other backwards planets. Kana Karr, Arch Swordsman, Third Class, has his first assignment on Fronn. However, there they find weapons that belong only to the Galactics, and mechanized Terrans, all illegal. They must fight the entire planet to find a way to return and warn Central Command.