If your player can justify it, they can take Channeling: Ectomancy, or maybe Channeling: Spirit.
Channeling: Spirit is going to have easy combat applications, like shields, blasts of force, veils.
Check out this Ectomancer PI I found online:
http://vinlandsolutions.site11.com/Products/DFRPG/SampleChars/DMW/PCG8_CD/JohnStrauss.htmlThe character has Spirit Channeling, but went the ghostly route (as opposed to the force route) with his Rote Spells, which display that he:
- takes on temporary ghostlike semi-incorporeality to justify Blocks and Armor
- channels simple force of will for an Attack (maybe it is raw ectoplasm)
- summons a helpful Poltergeist to perform Maneuvers.
Channeling: Ectomancy is going to be harder to find applicable special effects, but a looser interpretation of Ectomancy is the manipulation of Ectoplasm - not just ghosts/spirits. Although an Ectomancer shouldn't do the exact same things as a Conjurer, they could be able to summon and manipulate raw ectoplasm, perhaps creating slippery areas, temporary barriers, etc.
That said, most of the example powers in that PI character are spells I think would apply to a straight-up Ectomancer.