Velanna knows well the dangers of magic. She's been burned of course, but the fear she sees in the young apprentices in Skyhold, the fear she has seen in so many who knew she was a Dalish mage, that is behavior taught with Circles.

"I do agree, but without allowing growth, forcing mages all to fit into some... box, that is what creates dangerous mages. I have said this before, it is rare for a Dalish mage to become an abomination, because we are not taught to never explore the reach our power has, but to do it with caution." That and the Dalish generally don't deal with Spirits because they're considered bad news, regardless of origin. Velanna's friendship with Justice made her question that train of thought, and went to show that even the Dalish don't know all there is to know about magic.