Battle Mage (The Souls of Wrath) by Peter Flannery

An infernal army on the march. An unholy demon at its head. The one person who can stop it is a weakling nobody trusts.

Falco Dante knows only guilt. The son of a traitor, the sickly young man yearns to fight like the heroes of old. Instead, he earns further shame when he interrupts a dragon summoning, allowing a demon horde to destroy his village.

Desperate to make amends, Falco enters the demanding Academy of War in the hope of at last becoming worthy to defend the kingdom. And though he begins to unlock the magic within, the would-be champion fears it won’t be enough to defeat an invincible foe.