Helm: Haligtree Knight Helm

Armour: Haligtree Knight Armor

Gauntlet: Haligtree Knight Gauntlets

Leggings: Haligtree Knight Greaves

Where To Find: 

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

The helmet can be discovered on a corpse near the Elphael Inner Wall site of grace.

The other parts are dropped by Haligtree Knights, which are located in Elphael, specifically within the Brace of the Haligtree.