Our Lords of the Fallen Faithful Achievement Guide will go over the steps you need to follow to complete this optional sidequest.
Before taking on some of the later areas required for this sidequest, we'd recommend finding the Rune Tablets needed to upgrade your gear further. One area you'll visit is also home to a Lamp upgrade item, which is worth picking up as well.
How to Start the Lords of the Fallen Faithful Sidequest
The Faithful sidequest / achievement is tied to Stomund, Captain of the Fidelis. He can be found in the main hub area of Lords of the Fallen, after going through the Abandoned Redcopse area and defeating Pieta on the bridge.
After meeting him for the first time, Stomund will stay to the right of the hub area Vestige — make sure to buy the Pilgrim’s Perch Key from him, as it's needed for later.
After progressing through the game (generally around the time you reach Upper Calrath), Stomund will disappear from the hub area. He leaves a note behind, with his knights mentioning that "he's left for the manse".
Said manse in question is the Manse of the Hallowed Brothers. This area is reached by opening the door in the bellroom of Pilgrim's Perch Descent, then travelling through Pilgrim's Perch Ascent.
How to Find Stomund
You'll find Stomund right at the end of the Manse, through a gate to the left of the bridge to the Tower of Penance. He'll tell you that he must reach "Our Immaculate Lady", before allowing you to purchase items from him again.
After talking to him, head through the next area, the Abbey of the Hallowed Sisters. After you head inside and reach the room with the large tree, head up the stairs to find Stomund again.
He'll mention that there used to be a banner here, and urges you to find the broken remains so he can fix it. The banner is in 2 pieces, and both must be found before leaving the Abbey to finish the Faithful sidequest.
Lords of the Fallen Banner Locations
Damaged Standard - Manse of the Hallowed Brothers.
In courtyard outside the church, there is a door under the stairs (the ones leading to the area miniboss) that can be passed through in Umbral using your lamp. Once through, head down the elevator then go all the way to the end of the sewer. Going down the stairs at the end of the tunnel will lead you to the first part of the banner.
Tattered Banner - Abbey of the Hallowed Sisters
After defeating Rapturous Huntress Lirenne in the bloody church further in the area, go up the first set of stairs and head outside. Enter the Umbral realm and defeat the priest to get the second quest item.
After finding both pieces of the banner, head back to Stomund and hand them over. He'll thank you, before preparing to head off to the Empyrean (the area directly after Abbey of the Hallowed Sisters). If you want to buy anything from him, make sure to do it now.
Head into the Empyrean, and up all of the steps until just before the main gate. You can find the impaled body of Stomund, which gives his weapon and armor when interacted with. You also get the Faithful achievement / trophy.
That's everything for our Lords of the Fallen Faithful Achievement Guide! Make sure to check out more of our guides below.