Pedantic describes the attribute of being a pedant. It is like "employee" and "employed." Hopefully this isn't too pedantic, haha, but they almost seem too closely related to describe one as coming from the other.

You are asking whether pedantic is derived from pedant? I assume so. It can both mean like a pedant (emphasizing minutiae) or it can mean just dull, as we often think of classroom activities being dull, which is similar to didactic, although pedantic is probably only used in the negative sense where as didactic still has more neutral/positive usage in addition to meaning dull. So I am not sure if Pedantic ever meant generally to be related to teaching by design or intent.