Obviously sense the commander role only goes tot he highest xp player, the rewards and bonus need to be worth pursuing, but at the same time, I don't want to see the skill end up as a rich get richer skill where the higher players can, in some way, purchase needs to get xp at higher rate than any other player can like scavenger. I'd like to see the skill in a way that earning xp is rewarded based on effort, not pocketbooks.
As for bonuses, I could see the skill leading to a few things.
Perhaps good karma gets a small damage bonus to certain bosses, and bad karma gets a damage boost to other bosses. This boost could increase the higher your level gets.
Maybe good karma could cause an xp boost to certain skills (wood cutting, construction, agility, farming, cooking ect) and bad karma to other skills (thieving, slayer, gambling, summoning, hunter ect).
Maybe a passive could be placed on both factions. Good Karma could get a persistent 1 in 25 chance to hit double the max hit. Bad karma gets a 1 in 50 chance to do 4x max hit. (obviously numbers can be adjusted as I have no idea what would be acceptable values here lol)
These bonus, abilities, and passives could be elevated for the commanders of each faction.