In Herrera's room.
...
Link started his story from his arrival in River Cove Town, to his cooperation with the Flamingo Band of Mercenaries because he was desperate for money and finally to when they defeated the Dark Brotherhood and killed Viktor—which was where he got the Occultic Rune from. Link explained all that transpired in detail to Herrera without leaving anything out.
"It is almost indestructible," said Link, pointing to the Occultic Rune. "It is a sacred gear of the demons which undoubtedly contains a wealth of knowledge about black magic. My initial plan was to secretly study it, hoping to obtain power from it. But recent events have told me that I was too naive to believe that I could attempt that."