I will have to defeat Order of Rime shardhammers in order to get the last few pieces of matching armor (2 required). (They are autoupdates). The "An invading shardhammer" groups also count.
As in a number of other quests, you will likely have cleaned out two camps to complete part 1, then have to either wait for respawn or go to the third camp to complete this step (you cannot collect these "last few pieces" before you obtain the fourth satchel).
I should find Sliza Xarezia, a powerful illusionist within the city of Riliss, and give her the armor I obtained. ( -861, 58, -179 ) /waypoint -861, 58, -179