Well, since they appear to be almost spectral, you might be able to work in some rusty elements that could contrast nicely with the cool colors you have going on right now, but I'd keep the majority as you have it now. Something about it "feels" right with the cold colors. The "icy touch of death" kinda thing. The rust is just an idea for you though.
My armies: Empire, Dwarfs, High Elves, Wood Elves, Dark Elves, Lizardmen, Skaven, Tomb Kings, Ogre Kingdoms, Orcs and Goblins, and Skitarii (40K).