Kill a Remembrance boss with Remembrance weapon/spell only

This square requires that you defeat one of the bosses that drop a remembrance item using solely weapons or spells that are acquired by trading another remembrance to the Crone in Roundtable Hold.

The very nature of this square makes it not very rushable, as you need to kill a remembrance boss first, get the weapon or spell from that boss, and then obtain access to another remembrance boss and kill it with the remembrance reward. Also, the weapon randomizer makes it unpredictable and remembrance weapons can be difficult to wield due to stat requirements, in some cases requiring the use of Crystal Tears. Another potential inconvenience is not spending the remembrance for runes or having to duplicate the remembrance later.