Helm: Banished Knight Helm

Armour: Banished Knight Armor

Gauntlet: Banished Knight Gauntlets

Leggings: Banished Knight Greaves

Where To Find: 

(Click the link above to view the equipment and watch the getting video.)

Acquired as a drop from Banished Knight adversaries found in various locations, including Stormveil Castle, Cathedral of Dragon Communion, Castle Sol, and Crumbling Farum Azula.