I like Eöl with a black sword fighting along with the Dwarves!
We could make them shadow demons. Would work as well as ice demons in the far North, and would be logical when Tilion tries to bring light in different forms.So, there will be resistance to the idea of giving Melkor flying henchmen, but I have a potential solution.
There has been, however, talk of two things that may help us tell this story.
1) Having Tilion throw up the Northern Lights to help the Noldor crossing the Helcaraxe.
2) Having ice demons or some such attacking the Noldor.
Suppose Tilion is preparing for his first takeoff, and is beset be some creatures at the edge of the world, and their combat creates the Northern Lights?