Where to Get the Fire Knight Greaves
To acquire the Fire Knight Greaves, follow these steps:

Location: Scadu Altus – Shadow Keep Specimen Storehouse

The Fire Knight Greaves is a rare drop from the Fire Knights, which can be found on Elden Ring Items the seventh floor of the Shadow Keep Specimen Storehouse in north Scadu Altus.
To access the Shadow Keep dungeon, head north from the Highland Cross-site of grace. You’ll need to traverse the area and locate the main gate to enter the Shadow Keep itself.
Farming the Fire Knight Greaves

The Fire Knight that drops the greaves is located on the seventh floor of the Specimen Storehouse.
Once you defeat this Fire Knight, you may not always get the greaves as a drop on the first attempt, as it is a rare drop. If you don't receive them, head back to the Seventh Floor site of Grace and rest to reset the area.
Tip: To increase your chances of cheap Elden Ring Items obtaining the greaves, boost your Discovery stat. You can do this by:
Raising your Arcane attribute.
Equipping the Silver Scarab Talisman.
Consuming items that increase item discovery, such as Silver-Pickled Fowl Foot and Silver Horn Tender.