|Required & Bonus Attributes|
The Steel Set can be found in a chest behind an Illusory Wall in the Memory of Orro. The chest can be found by using a Pharros' Contraption in the room to the left of Benhart of Jugo. Then activate an Illusory Wall to the right of the next Pharros' Contraption, in the chests will be the Steel Set and a Fire Seed.
The description makes mention of an order of knights, who are most likely the Berenike Knights.