Also mentioned near the ends of Words of Radiance:
“Kal,” Teft said, voice getting even softer. “At the end there, right before you arrived . . . Storms, son, I swear I saw a couple of the lads glowing. Faintly, with Stormlight.” “What?”“I’ve been listening to readings of those visions Brightlord Dalinar sees,” Teft continued. “I think you should do the same. From what I can guess, it seems that the orders of the Knights Radiant were made up of more than just the knights themselves.”