My suggestion is to do something similar to what was done in Guild Wars 2. GW2 had a system for crafting items called the "Collection Log". This is where all crafting mats were stored entirely separate from your inventory. This was done because of the sheer number of crafting mats needed.

If this system were used for both crafting mats and gear it could save a lot of inventory and retainer space. For Gear, it would allow a player to catalog gear obtained and use that cataloged item for the glamour without having to have the item in their inventory or retainer (it wouldn't be equipable from there, players would still have to have the item to do that). It would also allow players a way to "collect them all" so we can see what pieces we still need from what dungeons/raids.

As for the crafting mats, the same could be done here allowing us to keep crafting mats separate from our inventory. My inventory needs a rest from all the random mat drops and glamour loot I have to keep.