This sounds like an awesome idea!!! I liked the idea of freelancer but the rewards were slim, being tied to one lord gaining influence rep money rewards and still being able to level your companions sounds awesome.
Idea time
1 whole lot of sub quests.
a. Lords village is being raided <bandits or lords> sends his retainer <you> to defend it. get lord influence, village influence, honor reputation. cons offending lord/ faction rep loss, Bandits send more assassin's/thugs to kill you. <cons if defense lost> huge rep loss with village/ lord or debt owed to lord for poor service.
b. Lords daughter/wife wish's to visit the villagers. Lord sends retainers on escort mission. raiders/kidnappers/enemy faction attack. If they are defeated rep honor money, if not Lord sends you out to restore your name by destroying their hideout/raid prison otherwise huge negatives.
c. Lord seeks to rise in power as king or lord of more lands, send you on missions to degrade other lords rep with king, or incriminate them in treasons.
d. even though they have assassination quest in the game, they could be more specific to the lords holdings.
2. Combat
a. Battle command if the lord chooses not to take the field.
b. Pre-assault skirmish's, Just like a rally battle, the city being sieged/about to be sieged needs to be raided, the lords retainers get to fight a pre-battle out side the walls with the perimeter guards, or sneak over the walls for a night raid.
c. Village patrols.
Just a couple thought on options for more content. I really like the idea, and I think it would give a lot more meaning to siding with a faction. Cause really all I do right now, is get my companions choose a faction I don't like, slaughter them till I have a force large enough to make my own faction.
Maybe have promotions from one lord to the next and end up the kings personal guard.