Skirt worn by the guardian of the shrine.
The Fire Keepers were robbed of light, to better serve as vessels for souls. Only those who cherish the writhing, searing darkness were given the keepers' black attire.
Found inside the Bell Tower behind Firelink Shrine on a sarcophagus near the bottom. You'll need to jump down from the upper entrance.
Part of the Fire Keeper Set
|Physical Defence||Elemental Defence|