CustomCategories
Custom categories are easy, fast, and efficient. You create a custom categories via the configuration menu, and then just assign items to that custom category.
They do have one downside and that is that they are very basic, they only match against an items ID and soulbound status so where you have an unbound item with an, eg, "of the Wolf" or "of the Owl" sufix, or the same soulbound item but with different enchants/jewels applied then both items would be assigned to the same custom category.
If you need that level of differentiation then you will need to create a Rule to handle it.