Magister Xenovia:
Go to Field of Whispers and defeat the Crokian, Dailaon, Crokian Warriors, and Parhit in order to collect the Dark Crystals.
You will need at least 5 of them for each experiment.
If you successfully carry out the experiment using the Dark Crystals, you will be able to produce Dark Oxide. I will give you the Cryptogram of the Goddess Sword in exchange for 3 Dark Oxides.