I think that while this option has the potential to bring something back to the banker position that was lost when realmwide food moving was taken away from it, there has to be some sort of restriction on just how often and how many nobles the banker can handle. Something like the militia assigning by generals could be used as a model. Don't let the banker keep handing it out all the time, or to everyone. Maybe give one or two, and then force him to recharge or something.
We have hours in the game. How about each transaction takes 1-2 hours? If the banker is traveling with an active army that eats up mobility really quickly. If he's at an allied city waiting for the army..well, it'd still take a few days to hand out to everyone. Even then he'd have to be carrying a thousand or two in gold and that's a huge risk for most realms finances no matter how you look at it.
