The path across the Miasma Marshes to Nevermore seems to be clear... Find out what's going on!
This bounty is available to complete after beginning Errand 131.
This is a rehash of the Eternal Knight fight, so travel to Perdida once again, then go into the town and exit to the north to be back at the Miasma Marshes, levitating all the way through the entire marshes past where you just fought. You'll eventually wind up at Nevermore; from there, make your way to the boss area at the end to find another black orb, and thus, the next boss: Knight Terror!
This will be your toughest boss yet; if you have them, bring your familiars that have high defenses so you can try for a direct assault. Each of his attacks are pretty powerful, and even though he moves pretty slow, standing idly by and casting spells isn't ideal, especially when you see his Onslaught coming. DEFEND and use All-Out Defense at all costs then!
As for the rest of the battle, keep a close eye on your HP while keeping your HP near max, and work on interchanging your strongest physical-based tricks and regular attacks.
Defeat it and you'll complete the bounty hunt, return to the Swift Solutions to claim your reward.