Just a small idea I had. I have been thinking about how to get the factions to play differently strategically, so that they all have very different play styles. One of the simplest ways is to give them each a different way of getting a resource. Since prestige is so important and could possibly come from different sources I have brainstormed a system where the generic prestige from sovereign levels has been removed, instead each faction has a government type that decides how they amass prestige. I know this would clash somewhat with existing traits but I think a much more streamlined and in your face system would be of great benefit.

Government Types

Reclaimers: Completing Quests

Expansionist: Unique outpost improvement.

Architects: Constructing special city improvements.

Tyranny: Leveling your sovereign.

Horde: Each trained unit produces a bit.

Conquerors: From winning fights.

Enslavers: From conquered cities and human deaths.

Enchanters: From unique spells and enchantments.

Heroism: Each champion grants a base amount that increases a bit as they level. 

Mercentile: Trade Routes produce it.

Darwinism: Killing and recruiting Monsters.