Let's return to the teleport point now, or use a Teleport Charm to teleport to "Cage Path".
After teleporting here, look to the left. The location of this Flying Guillotine is where we previously turned in the quest; go down from the right side.
Climb the ladder on the left, then jump to the platform on the right.
Open the door on the left and collect the three items inside.
The golden one is the Soulcasting material "Restored Treasure Cauldron".

