Helm: Foot Soldier Helm

Armour: Scarlet Tabard

Gauntlet: Foot Soldier Gauntlets

Leggings: Foot Soldier Greaves

Where To Find: 

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

The equipment pieces are obtained by defeating Radahn Foot Soldiers present in numerous fortified zones and encampments scattered throughout Caelid.

However, specifically, the Foot Soldier Gauntlets and Foot Soldier Greaves exclusively drop from the Godrick Foot Soldiers.