Who is Sholem (AKA Shoel) from Chapterhouse: Dune and what is their importance?

Rebecca's late husband, Shoel is used to describe the role and characteristics of a Truthsayer. He admits to finding the training nonsense until Truthsense, which has always been inside him, twitches. He hates what he sees in some people, but others are like beautiful flowers, innocent - like Rebecca. Shoel's memory helps Rebecca survive an encounter with the Grand Honored Matre Dama.