Alasteir has a point here... A Judge can hold court for a region if they are in said region. How about allowing the Banker to sell or purchase food for a region if they are in that region?
Otherwise IMHO you can almost remove the banker from the mix.
Thats too powerful though. IMHO, what would be balanced is if the banker could buy food for a region when it is starving, and be able to sell food that is not within the granaries. He buys with his own gold bonds, and gold from the food sold still goes to the region lord so the banker doesn't get rich from selling other lords food. He would also be required to be in the region.
