From FFXI Wiki
- Speak with Raibaht to start quest.
- Speak with Mighty Fist in Metalworks (G-9) (inside the forge) and you will receive a key item: Letter from the Darksteel Forge
- Travel to Windurst Waters and speak to Cochal-Monchal (F-8) (North Map - Optistery)
- Obtain a Yagudo Cherry from either a vendor or the auction house.
- Travel to Giddeus and head towards H-14 on the map. Please follow directions on the map pictured here, follow the arrows which points the direction to fall when your journey is hampered by a ledge.
- This next action will spawn a NM: Vaa Huja the Erudite which will link with other Yagudos in the area, so you may want to clear the area and prep before doing so. Once you have reached H-14, locate the ??? and trade the Yagudo Cherry to it.
- Defeat the NM and click on the ??? again. You will obtain a key item: "Darksteel Formula"
- Return to Metalworks and speak with Mighty Fist again.
- Return to Raibaht and speak with him to complete quest.