Create a function in your player controller that can handle this and shot it back to the inventory manager component and cast to it from your character if you need to, If your using actors for armor as well you could set a variable to the following item equipped, you can do this in the equipment inventory component where it sets the mesh, I probably will only use a actor for main-hand you can still set durability on a mesh only item, what you need to do is create a function that handles setting the durability on both the actor and the UMG version of the item, what i did to save on loops was add a variable to my item list called Inventory Slot then in added item i grab the slot and set it on the item, Now this is handy as you can just break the item and get its location without any looping, So your function just wants to get the item change its durability and then adds it over the top of your old item, and depending on its durability do your own logic like damage Nerf or destroy the item, handle that in your weapon actor or in the player controller for mesh based items.
Just a note make sure every one adds in a Is Falling check on the Input: Use Actor(Usable/Pickup/Container) or in mid air you can stop the character if you open a container lol.