Who is Sador from Unfinished Tales of Numenor and Middle-earth and what is their importance?

In the "Tale of the Children of Hurin," Sador is the woodsman that befriends Turin as a small child. It is Sador who Turin goes to with his problems, and Sador who is there for him. When Turin returns to Dor-lomin, he starts a revolt that costs Sador his life. With his dying breath, Sador begs Turin to leave.