Helm: Duelist Helm

Armour: Gravekeeper Cloak

Gauntlet: X

Leggings: Duelist Greaves

Where To Find: 

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

Obtained as a drop from Duelist enemies situated in Leyndell, Royal Capital. It's worth noting that this set cannot be farmed after defeating Maliketh, The Black Blade, as the Duelists vanish following this encounter.