Contained divine radiance.
He was an excellent human, and it was said that this Viscount was also a beast tamer.
As a beast tamer, he didn't keep the young dragon as a pet, which was quite commendable. In the words of the Holy Blue Humans, the Viscount raised the young dragon as his daughter.
When the young dragon offered him the Fruit of Wisdom, he didn't eat it but let the young dragon have it instead. It seemed that he knew the value of the Fruit of Wisdom and had heard of it, but whether he had ever seen one... that was difficult to judge at the moment.
Lance allowed the human-transformed Golden Giant Dragon to size him up. He had great confidence in his Art of Transformation. If this human-transformed Golden Giant Dragon could see that his true form was that of a Black Dragon, then this fellow must undoubtedly be a Dragon King-tier Giant Dragon.
Possible?