How to unlock: talk to Tarfos; you will find him East of Yduran's Wagon (M1,2).
East of Yduran's Wagon (M1,2), you will meet mayor Tarfos, who is talking to a group of villagers. After you talk to him, he asks you to help him solve a certain matter. As it turn out, there is an envoy from Defiance Bay in the village, sent in to negotiate a trade treaty. That's exactly your task. Every choice that you make here will affect the life of the villagers. It will also affect your reputation in Stalwart Village.
First of all, go to Gref's Rest (M1,7). At the counter, you will meet Nesta. Talk to her. She wants to take a closer look at the settlement. She tells you to meet her near the Fishery (M1,4). During the conversation, you will have to decide and tell Nesta whether the building should be kept functional or should it be closed.
Then, you will need to go to Stalwart Village Mine, in the north-eastern part of the village. You will find Nesta by the foreman's room (M2,2). During the conversation, you will have to decide whether to tell Nesta about Vithrack Caves, and voice your opinion concerning the presence of the Knights of the Crucible in the mine. If you support them, your reputation in the village will drop.
The last location that you need to visit is Durgan's Battery. As soon as you enter the location, you will be approached by Nesta chased by several warriors. You will have to defeat them. When the deed is done loot their corpses (they have quite a lot of gold on them) and go to White Forge inside Durgan's Battery (M5). During your conversation with Nesta, you will have to decide who is to work at the forge - the blacksmiths from Crucible Keep or the locals.
Now you have to report the outcome of the negotiations to Tarfos (M1,2). Your choices will be summed up and your reputation in the village will be updated. As a reward, you will receive some experience points and Tax Collector's Mantle which provides you with a bonus of +2 to Stealth, and grants you with 2 additional abilities.