Forgotten Realms: Silver Shadows (Songs and Swords #3)

Arilyn Moonblade has always feared the elfshadow, the essence of her sword's magic. When she learns the truth behind her moonblade, she vows to find a way to escape her fate. The half-elf seeks answers from the elves of Evermeet, but is asked to help a band of forest elves threatened with extinction. Posing as a moonelf warrior, she is drawn into the world of wild elves.