Like most members have already said, you can use parchment as a sort of transfer method and just to repeat Olofantur's idea: The parchment/document would require a signature from the bank, yourself, and your receiver in some sort of meeting? A secured transfer with all of you as witness?
Now, if you want to talk physical transfer, perhaps an carriage drawn transportation surrounded by armed guards? This could also be made into a RP scene/event if you want? I'm just throwing out the idea.
Now, if you want to talk physical transfer, perhaps an carriage drawn transportation surrounded by armed guards? This could also be made into a RP scene/event if you want? I'm just throwing out the idea.