Looking for the term for the relationship between "confidence" and "knowledge"
I cannot know what your friend or teacher ever told you, but you would be talking about cognizance.

Cognizance and Experience of Technology

http://staffweb.ncnu.edu.tw/clhung/MOT/papers/9.pdf

Knowledge base as a set of cognizance objects 

http://web.csulb.edu/journals/jecr/issues/20004/paper3.pdf