In Dalaran, only archmages of the sixth ring or higher were qualified to become mentors...
Likewise, one needed strength above the third ring to leave behind the status of apprentice or novice and become an archmage's student, provided they specialized in the same school!
As Prince Kael'thas had said before, Dalaran strictly regulated the number of students a mentor could teach... whether a sixth-ring blue robe or a ninth-ring white robe, they could teach no more than two students at a time.
Of course, this rule was not set in stone. If a mentor already had two students and took an interest in an exceptionally gifted young mage... he could submit a written application to Dalaran for special permission to teach three students!
A mere Karin Sunfury might have drawn a little of the prince's attention, but only a little! Clearly, that was not enough for Kael'thas to make such an exceptional application on his behalf!
The relationship between mentor and student was also sacred!
It was entirely different from the loose, nonbinding relationships of the apprentice and novice stages.
For a mentor, a student's future development could be a source of glory...
There had been an elderly mage in Dalaran named Losarks, who had died seven years ago. He had been only an ordinary sixth-ring blue robe, with almost no achievements in magical research throughout his life and no military accomplishments in the wars against trolls or gnolls. Yet in the portrait gallery on the highest floor of the Violet Citadel, his portrait hung high above those of countless seventh- and eighth-ring mages.
This was purely because he had another identity... the mentor of Archmage Antonidas, one of the finest mages in Kirin Tor history and the current chairman of the Council of Six! That simple identity was enough