A variety of Bhāva Nikṣepa (transferred epithet for an actualized state);
the epithet 'knower' given to the actualized state of 'knower' when he is an actual knower of the word under consideration as well as he is engaged in that activity (which is connoted by that word).
upādhyāyārthajnaḥ adhyāpanakriyāpravṛttaśca noāgamato bhāvopādhyāyaḥ.
(Jaisidī 10.9 Vṛ)