Ectomancy the White Council think is too close to Necromancy, but in their ignorance they do not realise that the two are diametrically opposed. Necromancy is all about forcing the dead into subservience, Ectomancy is giving the dead a voice and helping them to resolve issues with the living and within themselves. With Mort it’s not just a gift, it’s a vocation. Fitz was a minor talent in this area, Mort is a major talent.
We don’t know what Mort did during Battle Ground, he wasn’t in a position to take on the Necromancers so the was otherwise involved. He wasn’t in the pub. I like to think he was busy summoning Morgan and defending his neighbourhood against the Fomor. Morgan is Welsh, he would know about the Huntsman immediately and figure out a way to use Earth Magic to take out the entire group of 13 simultaneously, with Mort using ghosts as spotters to target them. Together they would be extremely formidable.
I could see Sir Stuart and Morgan being great friends, two old soldiers just fading away. I would like to see the ghost of Morgan brought back just to build upon Journal, but there is much you could do with the characters development after he dies, Morgan’s ghost can give exposition about Margaret, the Starborn and Harry’s loss into the adoption system