Cornell's grimoire has the alchemical symbol for the chemical element Arsenic on the front cover. This may hint at his specialty of enervating magic, as Arsenic is an element known for being poisonous to multicellular organisms.
Occasionally, he uses his grimoire to wake up students he catches sleeping in class, by either slamming it down loudly on their desk, or tapping them on the head with the spine of his grimoire.
He dislikes any puns related to his name.
Despite his role in abducting students for the Sahar, Cornell does genuinely care about his students' education. Seeing a student trying their best then excelling in their studies at the academy is something he likes, albeit unfortunately not as much as working with the Sahar on experiments.
He is fond of taking walks around Terminus during the evening or night to relax.
Cornell has a bad habit of hoarding knick-knacks and other random objects he has little to no use for, often under the excuse that he may need them in the future.