Elden Ring PC | Stonesword Key near Stormhill Shack site of grace

"Stonesword Key is a Key Item and optional Keepsake in Elden Ring. Stonesword Key can be used to break one imp statue seal. Key Items in Elden Ring include a wide variety of items found in specific locations or are given by a related NPCs which are used to unlock areas, quests, and to further progress the game's story."

Stonesword Key
https://eldenring.wiki.fextralife.com/Stonesword+Key