I think a Necromancer could work with spirits as well. One of the dictionary definitions of necromancy is, "the supposed practice of communicating with the dead, especially in order to predict the future." The Necromancers wouldn't necessarily have to summon dead bodies, and it could still keep its identity as one who deals with the afterlife.
EDIT: Of course, thinking on this, it leads me to consider the possibility of a job called an Animator, who has the power to absorb and produce aether, shaping into the image of defeated foes. The illusion of calling upon the dead, when the beings are truly neither alive nor otherwise.