A dragon-mage or dragon wizard is a dragon who uses human magic.
In the Course Books
Hrethrel Jusenkyou, of the High Mountain Flight, was a distant relative of Draco. Hrethrel lived during the mid Sixth Age; he was not notable and lived a normal lifespan, but was a highly skilled enchanter.
Thorner, another dragon of the High Mountain Flight, would also become a dragon-mage, but does not emerge as such until after the events of the Course Books are over. He appears in the Consecution Books, over 3,000 years old, following in Draco's footsteps. Thorner is a direct descendant of Hrethrel.