Sam Finch and the Zombie Hybrid by J. W. Bouchard
Sam Finch is a frail but exceedingly intelligent boy whose lifelong aspiration has always been to attend the Dashelmore Warrior Training Academy. When Sam turns fifteen, his wish finally comes true. About to leave home for the first time, little does he know what is in store for him as he finds himself physically outmatched, falling in love with two different girls, and illegally learning to do magic on the side. And then there's his secondhand sword named Rusty, which seems to possess secret powers despite being far past its prime. But those are the least of Sam's worries after he soon discovers that there is something far more sinister on the horizon which threatens the existence of the entire world.