This is a condensed guide for the “Save the Queen: Blades of Gunnhildr” questline for Shadowbringers.
A much more definitive guide can be found here.
− Level 80 Job
− Completed Shadowbringers
− Stormblood Alliance Raids
Detailed Requirements and links to other quests can be found here
The starting quest for the relic is called Hail to the Queen and a full listing of all quests can be found here