I agree that there's no commonly used term for what you want to describe, and "knowledge haver" is just as problematic. Ideally, people will alternate between being a mentor and learner throughout their lives -- the process never ends.

Btw, though my article on this matter is ballooning, the advice for "teachers" amounts to:

a) Actually understand the subject matter yourself, in the sense of having a model that connects to your understanding of everything else. (Obligatory plug: that means Level 2.)

b) Identify the nearest point of common understanding ("nepocu"), and work back to your own understanding from there.