The quest begins by traveling to Daguerreo (click on the link for more information). Speak to the old man near the library on the third floor. He asks that if you find an item called the “Magical Fingertip” that you bring it to him.
Travel to the Auction House in Treno. You now need to purchase each of the following items and sell them to the corresponding people:
Doga’s Artifact which can be sold to the Scholar in the Synthesis Shop.
Une’s Mirror which can be sold to the Nobleman just outside the Synthesis Shop.
Rat Tail which can be sold to the Adventurer who is also just outside the Synthesis Shop.
Griffin’s Heart which can be sold to the same Adventurer.
Return to the Auction House after you have purchased and resold all four items and the Magical Fingertip will appear as a new item that you can bid on. It can cost anywhere from 40,000 gil to 60,000 gil depending on how lucky you get. Return to Daguerreo with the item and present it to the old man to receive the Excalibur sword as a reward for completing the quest.
The Excalibur sword is by no means Steiner’s strongest weapon but it can teach him the Climhazzard skill.