The Ever Illustrious Regalia - Hammerhead
First Available: Chapter 7
Other Requirements: Complete The Ever Valorous Regalia
Rewards: 3,000 EXP & Enhanced Headlights for the Regalia
This is the second to last quest offered to you by Cindy that began with The Ever Regal Regalia Side Quest earlier in the game. You can technically complete this quest prior to finishing the game's story line but it'll take a lot of leveling and preparation to do so prior to completing the game.
For this quest you will need to visit the Crestholm Channels dungeon which is in the same area where we first began the game. All of the enemies in this dungeon are Daemons and level 45+, unless you're level 50+ with your team (minimum) expect to use a lot of consumables while hunting in this dungeon.
You'll find the Enhanced Headlights for this quest near one of the final panels that you have to activate to fight the last boss for this dungeon. The Enhanced Headlights are actually on one of the first floors you visit of the dungeon but you'll be unable to reach them due to locked doors. What you have to do is first travel to the bottom of the dungeon and then work your way back up, this will put you on the proper side to pick up the headlights.
If you're still having trouble locating the Enhanced Headlights, use my screenshot below or check out my Crestholm Channels Dungeon Guide. That will go into more detail about the dungeon as a whole and hopefully help you find the item you're looking for.
The reward for this quest is Enhanced Headlights for your Regalia. If you're unsure what they do, it repels Daemons while you're driving the Regalia someplace during the night time.