Dragon Age: The Veilguard

Throughout northern Thedas there are a number of faction merchants i.e. Antivan Crows has a merchant in the Cantori Diamond in the Treviso Canals, and the Shadow Dragons has one in the centre of the Sanctum in Dock Town.

Once you have enough money, some specific materials and also enough favour with the relevant faction, you’ll be able to rank up a faction merchant to get access to better stocks. 

While you can upgrade all of the game’s 6 factions to rank 4, you only need to upgrade any of them to level 2 to unlock the ‘A Faction’s Favour’ achievement.