Black Light Burns

Turn around and travel towards the Main Scenario Quest Marker , which leads towards the “Lazarus District” area of the map. When you first enter the town, a pathway on the left side of the screen will lead up to an open area. There is a treasure coffer on the back wall of this area that contains ten spools of
Steelsilk.

Walk down towards the center of town and make sure you still have your multi-target Eikonic Ability Set activated. Defeat the group of Lazarus Bandits, focusing on the magic spellcasters first.

A short cutscene will trigger at the end of the fight. After Sir Wade and Clive are done speaking, and you’re back in control of Clive, turn around and look for another treasure coffer on the ground near the wall that contains ten pinches of Magicked Ash.
Speak to the “Guardian Quartermaster” in this area, and you can now buy the Demontamer’s Armguards that should have been in one of those treasure coffers from earlier. Afterwards, exit Lazarus and hop on your
Chocobo to make your way back to the bridge.

Black or White
A brief battle ensues here. The first wave consists of Black Shield soldiers. That group will be joined by an Imperial War Wyvern, which is similar to the other wyvern-type enemies you’ve faced before.
Lastly, you’ll face another dragoon-type enemy, the “Knight of the Lasting Dark”. These are all enemies you’ve faced before, and they don’t require any extra strategies to defeat; in fact, they should be easier to beat now that you have extra Abilities and a higher-level character. There is no Medal of Valor to earn for this fight.

A few cutscenes will trigger once the battle is over, and then it's on to the next Main Scenario Subquest.