Welcome!
I played a 2v2 with Nightmare AIs when I saw a FoG striking to a group enemy reinforcements. War rank was under 3 for both team, so no Citadel upgrade. Only AIs, and it wasn't me. Was it a Heavens Wrath that my UB ally casted?
I didn't notice an early speed boost or a health boost or anything that can be given by Favor Items on AI Demigods...
So I'm asking you. 
Can AI get Favor Items?
Thanks!
Daedrick