To get Ofieri Armor set you need to find 4 pieces of Ofier gear and four diagrams which are in foreign languages. The Ofier Armor set is a level 35 Witcher Gear in this very first DLC. Here is how you will find the Ofieri Armor diagram location and how to built one in The Witcher 3 DLC Hearts of Stone.
The 4 pieces of Ofieri gear is needed to Built the Ofier Armor set. You'll find these pieces in the quest From Ofier’s Distant Shores. During this Task, you'll find the four diagrams in a foreign language. Check the exact location where to find the diagram for Ofieri Armor.
Ofieri Armor Piece 1
The Boots diagram can be obtained in a bandit camp
Ofieri Armor Piece 2
The Gauntlets diagram can be obtained in a tent near the ruins south of Upper Mill.
Ofieri Armor Piece 3
The Chest piece diagram is in a hideout underground in the southwest of Erde.
Ofieri Armor Piece 4
The Trousers Diagram can be obtained from a hut in of Brunwich.
Take these diagrams to an Ofieri Merchant in Upper Mill. He will convert the language and craft the pieces such as Ofieri Scale Armor (chest piece), Ofieri Shalovary (trousers), Ofieri Gauntlets, Ofieri Boots.
How to get Ofieri Saber
To Obtain Ofieri Saber go to the Ofieri merchant in Upper Mill as he sells one himself. Also do check the stats before you pick as they both are silver.