I think this has been suggested a couple of times, but I'm going to suggest it again. Why is this not a thing yet? I know you should not compare Emps-World to Oldschool Runescape, but this really is a nice and simple quality of life feature there.
A lot of monsters on Emps-World drop unnoted herbs. This causes your inventory to fill up pretty fast. With a herb sack, you can simply put them in there to save inventory space and not let them go to waste.
The herb sack could be used while farming herbs as well so you don't have to bank as many times as you have to now.