If you equip an item and have no more pack slots, it will take the auto-unequipped item and put it in bank window, in place of the previous item.
IE
Equip one handed weapon into slots when 2 dual weilds are equipped. Due to lack of pack space, the first dual wield goes into bank.
Hope this is beneficial and works fully, I just did it at ruins.
Thanks for great site,
Kazuki
EDIT
Actually, you don't even need anything in second dual wield, any item previously equipped in that slot will move to bank. Good way to do far seas banking.
