The Battle for Castle Kvatch
Quest From: Savlian Matius;
After you retake the Kvatch Chapel, Savlian will ask you for further help in fighting for the city. Agree and follow him. Defeat some monsters and talk to him again. Go back to the Chapel and talk to Berich Inian about the key. Follow the map markers until you reach the mechanism that opens the castle gate - use it, and you'll meet up with Savlian's men again.
Defeat the daedra occupying the courtyard, talk to Marius again, and enter the castle. He'll tell you to find the count. Follow the map marker again, fighting off the daedra, and eventually you'll find count's body. Take the ring from it and go back to Matius in order to give it to him. You'll get a Kvatch Cuirass as a reward.