Since Zero can't trade/sell his weapons, it makes it harder for them to switch classes especially if they've alrdy invested into arcane weapons. I feel that this should be done so that Zero players can invest in the class while also being able to switch more easily if they want to main other classes. If being able to unequip their weapons to sell is too much to ask for, then maybe even being able to take out the essence of their weapon would be fine.