As it stands, most favor points are rewarded for offensive abilities. If Sedna is doing her job in a multiplayer match, she'll get fewer kills than the more offensively-oriented demigods. Healing should give some sort of bonus assist credit to make up the favor point gap.
Take a look at http://pantheon.demigodthegame.com/demigods/
Sedna has less than half of the favor points, but quite a bit more than half of the total playtime of Unclean Beast.