Aery vs Comet
The more I think about it, the more I think the best route to take for Aery and Comet would be to simply make Comet follow Aery's targeting style (go flying out and clock someone when you damage them from any source, orbit for two seconds, then start returning) while turning Aery into a pure shielding tool. People just plain DO NOT like the unreliable nature of Comet and as long as Aery is a reliable damage source, it's going to be preferential.
To keep Comet attractive to sustained damage Mages, the keystone could increase it's return velocity a little bit each time you damage the target.