The Sealed Missive
In the North-Eastern part of Elmshore, you find the Dying Monk (M35,4). Talk to him. He asks you to deliver the titular missive to the members of the order in the Twin Elms. You can either place the missive in your inventory intact, or break the seal. In the latter case, you learn about the artifact hidden under the floor of one of the houses in Elms' Reach.
Reach Hearthsong in Twin Elms and take the elevator to the Celestial Sapling Inn (M36,2). In one of the rooms, you meet the High Monk, who you can give the missive to. You will be rewarded with positive reputation points for Twin Elms.
During your meeting with the High Monk, you can lie and say that you received nothing from the dying monk. Also, you can try to find the item, mentioned in the document, on your own (you do not need to break the seal - you can simply follow this walkthrough). For this, you need to go to Elms' Reach, which neighbors Hearthsong. Enter the Northern Glafanthan Home (M37,3) and enter the Stealth mode to locate a secret stash in the floor. You can now collect the rare light armor.