Beyvin was the former keeper of the Rune of Honesty in Moonglow and the husband of Penumbra. However, he'd died prior to the beginning of Ultima VI and the Rune was buried together with him. So when the Avatar needed the rune, after getting the news from Penumbra, the hero asked Beyvin's cousin Manrel, who allowed entrance to the catacombs for the promise of delivering some flowers to the grave. The Avatar did so and found the rune in Beyvins remains.