Borg was not stacking arrows into a quiver which was already loaded. He needed to know that some items stack in the quiver.
He also needed to be able to combine multiple short stacks of arrows in the quiver. He had several quiver slots occupied with identical arrows all in short stacks. He can now combine those into one quiver slot.
He was buying enchant scrolls even though he had the spell. This was an encumbrance issue and showed up under a rare overweight window.