Evlana is mentioned in the Hunter's Blackbow and Hunter's Hat descriptions. Her descriptions state that she was not in fact a goddess, but rather a highly skilled bow huntress. Long after her death people began to believe that she was a goddess due to the passing of incorrect lore.
Her bow resembles the Black Bow of Pharis found in Dark Souls 1, which was also black and had a very long range. It is likely that they are one and the same bow and that Evlana either found or inherited this bow.
Her hat resembles Pharis's Hat in Dark Souls 1, but (as they change depending on gender) it resembles the hat that men wear.
Her symbol on the Name-engraved Ring appears to be a red bat (or a bat with a red background).
The following is content that was cut from the game but relates to Evlana:
Hunter's Hat description:
A commonplace leather hat with a feather. Traditionally used by bow hunters. The wildfowl Coco was ever-loyal to the goddess Evlana, and hunters place its feathers in their caps in hopes of receiving the divine protection of the famed bird.