Logically the eyes of Hraesvelger, Tiamat and the other two first brood dragons should work in a similar manner to Niddhog's. In fact any dragon of sufficient age should work. After all all they do is soak up aether over the centuries and so long as that aether is not spent on anything it should still be there. Which makes me wonder why primals are so dangerous for soaking up aether when its fine for dragons to do it.