I like this. Somehow I would like to see the vice marshal included in this. Perhaps the vice's leadership / 2 could be added to the marshal's leadership when both are present.
I am sure all numbers need to be adjusted so that bonuses are meaningful without being the only thing that matters.
It would be no problem, the vice-Marshal would add a bonus of 1/3 or 1/4 of his Leadership to the Marshal Leadership.
Of course, probably all numbers must be adjusted, but if the 'mechanism' works, the rest it's only minor matters!