If an existence value is high, the concept is true and objective and real. In this sense, essence goes with ontology. To shift from matter to a great thought is still conceptualizing. Both can have high existence values. Ontology emerges from epistemology when organisms evolve sufficiently to conceptualize.
Ontology is cultural.
I use 'ontic' as a short form of 'ontological'. The dictionary notes that 'ontic' refers to the real rather than the phenomenal, while it defines 'ontology' as the study of levels of existence. I see these terms as, at least, related, if not interchangeable. Again, I have no idea what is meant here. I have completely lost Nunn here.