The ancient Romans had much more strict naming conventions than the Greeks did. I'd recommend starting with the Wikipedia article to give you some idea of the structure involved:
http://en.wikipedia.org/wiki/Roman_naming_conventions
For Greek ideas, maybe try browsing the encyclopedia of names here:
http://www.theoi.com/Encyc_A.html. Aex/Aix and
Pallas look like they were unisex.
There are also lots of great names there that while perhaps not traditionally used for both sexes, a modern reader would have little trouble accepting as unisex, like
Enyo and Macris.