With the inclusion of Loadouts, people already have a good way of organizing sets of equipment and change between them, but didn't at least once, when getting a new costume piece, when getting a new weapon, when searching how many Ecto Drops you have and if you beat the server record, that is a bit tedious to search something specific in your Arsenal?
That is why I suggest something I will call the Storage Backpack!
What is the Storage Backpack?
The Storage Backpack is a filter which will show/hide items depending if you activate it or not. It is a optional feature, but it would most likely help you control what you care most in your Arsenal.
How would you use it?
When selecting an item in your Arsenal, the option "Move to the Storage Backpack" would show up. Selecting that and confirming it, would hide that item from your view when in the Arsenal. There, cleaned space! But as said, it is just hidden from view. You can do this with everything, even already equipped items - you can with Loadouts still have quick access to them without exchanging views.
Exchanging views:
Once you have in your Arsenal only showing what you care most, if you feel the need to check everything you have again, a toggle option would be in your Arsenal window: Show your Storage Backpack - And of course, activating that would deactivate the filter and show everything again in your Arsenal. A different shade of colour or an icon would show if something is hidden in your Storage Backpack from your view or not, and if you want something back in your non-filtered Arsenal, you can select that option (Remove from the Storage Backpack) by just clicking your item of choice.
This would help everyone in selecting things the easy way and create Loadouts faster when getting new equipments. As for this option, would it be an already implemented thing for free? Would you pay for that? With nothing more to say, until next suggestion!
I was just thinking about this! I'm returning from before the mission update so I'm slowly gaining a collection of weapons from the missions and it would be amazing to have some way to categorize or store them so they do not clutter my inventory (I could sell them, but I'd like to keep them for when I adventure with friends in lower tiers). It would also be great to store items that you don't plan on using but are waiting to upgrade, get UVs or trade, as this way you run no risk of accidentally selling/trading them. Which, admittedly isn't the biggest deal but it would definitely be extremely helpful.