Once you have flagged this quest you will be able to open the coffers for the Rogue's Culotte and Rogue's Vest.
Speak to Guslam at H-8 in Upper Jeuno in the Durable Shields shop and accept the quest. Once you have flagged this quest you will be able to open the coffer for the Old Gauntlets.
Touch the torch again (make sure you touch the same torch you used to spawn him) to receive the Shadow Flames (key item).
If other players in the party also need this key item, they can touch the torch as well - you don't have to fight him for each person.
Head back to Port Jeuno and click on the ??? at the toolbox for a cutscene. This completes the quest.
The Rest[]
Guslam mentions something about armor scattered about Vana'diel. You can find two more pieces of armor by simply opening coffers in the following zones:
You can either farm for the appropriate keys to open the coffers, or use a lock-pick of some sort.
Notes
Even though this is the lowest level piece, you cannot get this quest first. You must have started As Thick as Thieves (AF2) before you can start this quest.
If you have any other Borghertz's Hands quest active you will need to complete that one before you can get this quest.
After starting the quest, you can obtain the rewards in any order.
The quest is marked complete upon obtaining the gloves.