Could we either get rid of the memento system limitations, or give us a way to buy the limited timed event mementos from the kiosk with either exotic ciphers and glimmer(like everything else) or any type of in game currency. Gives people a chance to A. Get what they either missed out on, or got unlucky with not getting the memento during said event B. Spend ciphers if they already have every exotic so it isn't wasted currency.