I know there are 2 sterling treasures you can get once in a week, trying to complete my spektar titan armor set, all I need is the head. However, in the dawning, I remember getting 3 sterling treasures, I think I got one because I had 10 silver dust, I know you can get 1 sterling treasure by doing prison of elders each week, but how do you get the other one? Or is it just 1 a week?