Guide:
Adorns Valano’s terrace skyshard is hidden in the southeastern Auridon area, just north from Eastshore Islets Camp, or to the northeast is you are comming from Vulkhel Guard Wayshrine.
Enter the Valano Manor, head to the second floor, open one of the Silsailen doors and claim your prize. Although, the house is surrounded by big trees, you can easily spot it on the balcony.
Note: In order to be able to enter Valano Manor you need to be on a quest Teldur’s End.
You don’t have to be on the quest. There’s a “secret” entrance around back by the beach. Take the ladder inside the manor.