Trial by Sorceryby Richard Fierce

... if you don't bond with them first.
Eldwin wants to follow in his father's footsteps and become a Dragon Guard, but not for the glory. With his family dead and their lands dying, the opportunity to join the dragon rider school is all he has. But before Eldwin can bond with a dragon and guard the skies, he must pass three tests to prove his worth.
Compassion, magical aptitude, and armed combat.
He's determined to pass, but his maimed arm is a constant reminder of his disadvantage. Will the obstacles Eldwin faces keep him from reaching his dreams, or will he finally see what it's like to ride the skies?
Fans of Sarah K.L. Wilson's Dragon School, Christopher Paolini's Eragon and Anne McCaffrey's Dragon Riders of Pern will feel right at home.
Trial by Sorcery is the first episode of the series Dragon Riders of Osnen.