Anduin's True Class

[Aeriel]

(not to go totally offtopic, but what are Gelbin's and Gallywax' classes?)

But yea do we even know who Anduin's mentor or whatever is?

But too bad hes sort of priest, while Velen and Tyrande are still 'round...

High Priest Rohan in IF is set up as Anduin's mentor in "The Shattering".
Anduin then sets the stage for someone to become a Pally.
As for the people saying Anduin is partly "warrior", that is made very clear to NOT be the case. Varian wants him to be a warrior, but Anduin is not cut from the same cloth as it were. He is essentially the male equivalent of Tyrande.