In Mortal Shell 2, Merchant Vlas's side quest is a rather unique task. To start it, take a shortcut from the outskirts of Marmor to find Vlas. While Vlas sold upgrades in the first game, he seems to be just an NPC in the sequel. Ignore nearby enemies and head straight to the Path of Absolution.
How to Complete Merchant Vlas's Side Quest in Mortal Shell 2