I have spoken to Alys and the Minstrel and been instructed to "Use the Duty Finder to confront the Ultimate Weapon."

According to:
http://ffxiv.gamerescape.com/wiki/The_Ultimate_Ballad

※The Minstrel's Ballad: Ultima's Bane can be accessed via the Duty Finder

The problem is, there no entry in my Duty finder for this.
Is there some other duty I must complete to get this added?