Ferren Barr was definitely unhinged. And he was willing to sacrifice the Mon Calamari to plant the seeds of the Rebellion, so as to speak. I'd say he was a Dark Jedi by then, Padawan or not.

The Tenth Brother was a Jedi Master who worked with Mace Windu in that Mace Windu comic set in the Clone Wars. Have you read that? If not, maybe you should hold off on stats for him until you do.