The moral sense of the books becomes confused in the film. For example: Arren's murder of his father in the film is unmotivated, arbitrary: the explanation of it as committed by a dark shadow or alter-ego comes late, and is not convincing. Why is the boy split in two? We have no clue. The idea is taken from A Wizard of Earthsea, but in that book we know how Ged came to have a shadow following him, and we know why, and in the end, we know who that shadow is. The darkness within us can't be done away with by swinging a magic sword.