Mage-Guard of Hamor by E Modesitt Jr L

Rahl was a young apprentice on the island of Recluce sent to the mages training school for testing, then banished to Hamor. His education now continues under dangerous circumstances. In Hamor, his powers have increased, but so has the amount of trouble he attracts. The whole society of Hamor is a new culture for Modesitt - and Rahl - to explore, one in which magic is a monopoly of the state. Rahl is a mage now, powerful and still just as dangerous to himself and to others. This is the story of how he gains both more knowledge and power, and more self-control.