I'm no expert on the lore of conjuration, but it's my understanding that it involves transporting creatures from the planes of Oblivion and binding them to serve you temporarily. So, Arniel is in Oblivion, then? Does this mean the dwarves are also in Oblivion? Could they theoretically be summoned, like Arniel's shade can be? Or is summoning shades different to summoning daedra?
Maybe the experiment wasn't a success, and something else happened. Perhaps Arniel disappeared, but not in the way the dwemer did - was he killed by wielding Keening, and then svcked into the soul gem?
I'd be interested to know others thoughts on this!


) in original D&D lore shades are more like tortured souls of people who were evil or not very good in life so they likely wouldn't end up in Sovngarde I don't think. And, yeah, it's not clear how/why we're able to summon his shade. Maybe he was considered evil by the Divines and his punishment is having to serve us when we summon him because we did the world a favor by facilitating his removal? 
