Wood Angel, by Erin Bow

Plain Kate lives in a time afraid of magic. She has a gift for carving ‘lucky’ wooden-charms. Known as Witch-Blade, her unusual gift attracts dangerous attention in a place where witches are burned. When her village falls on bad times, suspicion falls on Kate. Scared for her life, she seeks the help of a mysterious stranger. In exchange for her shadow, the stranger will assist her, but Kate becomes part of a terrifying plan, darker than she ever dreamed.