A common bank box for all of your chars in the same account.
I've seen this done elsewhere under POL 97, but not sure I've ever seen a run uo version of it. Basically you had an account bank box and then one for each character. The account bank box was accessed by saying bank, the ones for the chracters you said personal bank.
I played a Pol shard that also had a similar feature but we didn't get access to our other characters individual bank boxes, but all characters on the account had access to the Account Bank, but then on that shard 99% of the shard didn't have a house (houses were restricted as to what already existed and the important ones in each town belonged to the player who was declared as the mayor of the town :-/
I, too, played on similar POL-based shards with that feature, but as Rithik mentioned, not all characters had houses on them. I don't really see the usefulness of this sort of feature where everyone gets a free house with their account. Characters can simply swap items and gold through secured containers in their houses.