Damaged Soul: When Cadogan was a young adult living in the city of Sanctimonia, he was attacked by a shade. While lucky enough to survive the experience, his sacred field was damaged by the creature. Along with the physical side-effects, Cadogan's ability to weave magic was reduced to almost nothing. Weaving a simple spell without assistance takes extra time and greater effort on Cadogan's part, and is likely to leave him exhausted in short order.
Knowledge (Cognimancy): Before Cadogan was born his father was a traveling entertainer who used his skill in magical illusion and divination to eke out a living on the road. It's from his father that Cadogan learned what he knows of weaving magic and cognimancy. Unfortunately for him he took his magical teaching for granted, and as such only has an apprentice's understanding of the school. Cadogan is further impeded by his damaged sacred field, which limits his energy to weave any sort of magic.