After you learn more about the amaro, you return to Seto to once again request the crystal shoes.
Requirements
This quest is available if you have completed the quest The Elder's Answer.
Starting the Quest
Talk to Urianger in Il Mheg to begin the quest.
Speak with Seto
Go to the quest icon on the map and talk to Seto. There will be a cutscene.
Speak with Seto Again
Go southeast to where the orange arrow is pointing in the minimap.
Speak with Seto And Defeat Any Sin Eaters
Talk to Seto, then defeat the four Forgiven Cowardice, then defeat the two Forgiven Conceit, and finally the Forgiven Deceit.
Speak with Seto Once More
Talk to Seto again to proceed.
Speak with Seto Once More, Again
Go northwest to where the orange arrow is pointing in the minimap and talk to Seto to complete the quest.
Aether Current Quest
With the completion of this quest, you can now start the blue quest "A New Amaro" in Il Mheg. Completing that quest will attune you to an Aether Current in this area.
Next Main Scenario Quest
After you complete the quest, talk to Seto to accept the next quest: Memento of a Friend.