Defiant - Alfurian Chronicles, #1

On the wild planet of Talamh, humanity thrived......until the alien Alfur conquered their world. Now, defeated and broken, humanity serves their immortal overlords. And pleads to the stars for a hero. Rydian Holt is nothing, nobody. Just another human from the streets of Talamh. Or at least, that's what he thinks-until his mother is caught up in a fledgling resistance group. Branded a traitor and sentenced to fight in the arena, now Rydian must face hardened gladiators in single combat.
To survive and advance through the ranks, he'll need the help of an enigmatic weapons master-and more than a little luck. But after a lifetime of servitude, survival is no longer enough for Rydian. He seeks a way to fight back- not just against his fellow gladiators, but against the Alfur themselves. If Rydian can uncover their greatest secret-the truth about the mysterious Light that powers their world-he might just win his freedom.