Inside the guard tower on top of the hill next to the sword to become Mol-Rehan Cancellor (star symbol) there's a locked Magic Chest.
The key to this chest has a name, "Magpie" (screenshot). For its location check the screenshot and the (rhombus symbol).
To find this one I had to look up the DB, google wasn't helping...
http://steamcommunity.com/sharedfiles/filedetails/?id=583588311