I have some skins and when I right click them, it has the options to “use” and “store in vault.” I when I click on “store in vault,” the item disappears but appears in my vault and I have to use a transmutation charge to use the skin. When I click on “use,” I can use it without the cost of a transmutation charge and the skin will still be unlocked in my vault. I only tested this with some toy skins and masks and on one character only though.
Why would I ever want to “store in vault”?