House of the dead duology

"In the Dominions, the dead linger, violent and unpredictable, unless a bonesmith severs the ghosts from their earthly remains. For bonesmith Wren, becoming a valkyr--a ghost-fighting warrior--is a chance to solidify her place in the noble House of Bone and impress her frequently absent father. But when sabotage causes Wren to fail her qualifying trial, she is banished to the Border Wall, the last line of defense against a wasteland called the Breach,...