LogFAQs > #972350399

...Oh, actually, I probably should post a list of the relevant details, huh

https://kiseki.fandom.com/wiki/List_of_master_quartz_(Cold_Steel_IV)

Joshua gets Zephyr and Tempest from this list. Estelle gets Skuld and Brigid.

https://kiseki.fandom.com/wiki/List_of_orbal_arts_(Cold_Steel_IV)

And they get the relevant arts in the master quartz list. Their Brave Orders respectively halve team turn delay for Joshua (so, just constantly taking more actions, which jives with how his time quartz gives him auto-haste and he has a Quick-type orbal art), and Estelle's cuts damage taken by all allies in half. They're actually remarkably well suited for the roles they're likely to take up in this particular fight, honestly.