I do not play in either SL or IS, but reading a bit more of the Lore of AION http://gameguide.na.aiononline.com/aion/Empyrean+Lords
I like to keep Siel and Israphel names, and the names have tradition.
But a more server-neutral name would be the other two cardinal lords Azphel and Ariel, but they are a bit faction oriented, but It is ok.
Another pair of names could be Ereshkiga + Fregion