Find the Small Private Altar Site of Grace: This Site of Grace is near a small courtyard patrolled by a Horned Warrior. The greaves have a chance to Elden Ring Runes drop from this specific enemy, so it’s a good idea to focus on defeating this warrior.

Defeat the Horned Warrior: Engage the Horned Warrior in the courtyard. If the Horned Warrior Greaves doesn’t drop immediately, simply rest at the Small Private Altar Site of Grace to respawn the warrior and try again.

Repeat as Necessary: The Horned Warrior Greaves are a rare drop, so you may need to defeat the warrior multiple times to acquire them. Keep resting at the Site of Grace to Elden Ring Runes buy respawn the Horned Warrior and speed up the process.