Heres a suggestion for a couple traits...

Son of the King: Being son of the king makes you quite influential among the faction +2 infuence (only available to factions that have kings hehe)

Brother Of the King: Being Brother to the king is a great honor. +1 infuence
(only available to factions that have kings)

Maby one for the faction leader when the faction increases a certain number of provinces, like "Great Leader of His people": This man has made his Kingdom/Empire/etc?? Greatly stronger and will be remembered among his people for centuries to come +4(?) infuence

there that should be good as i cant think of anymore