Metal Slinger (Fire & Metal #1) by Rachel Schneider
Summary (from the publisher): Even though she's not one of them, Brynn has spent her life among the Alaha, training to be a guard and waiting for the chance to attend the annual market hosted by the Kenta–the very same people who exiled her adopted community to a life at sea. Going to the market is a rite of passage eagerly anticipated by all young guards, but Brynn does not anticipate breaking a century-long peace treaty while there. Nor does she plan for the intense encounter with an enemy soldier that now threatens to unwind the fragile coexistence between their people–and everything Brynn once believed about herself to be true. Brynn's loyalty to the Alaha is tested when the truth of her identity is brought to light by this soldier who's taken an oath to bring her back to where she belongs. Narrowly escaping death on the violent high seas, Brynn's connection to the Alaha is further tested when she learns about the world of magic she's been denied. She was on...
