At first I though it was a bit too low for Marshals too, but if you want it to have any effect in the gameplay, it can't be much more higher... maybe one or two units more, at best!... I think...
How about the same thing except a marshal starts at 4 or 3 nobles instead of 1, but it has same progression and same bonus/penalty. You can't call the guy a marshal if he only leads his troops.
