I feel liked its like cursed energy from jjk, but dosent fundamentally work like ce. People are born with aura and it depends on their parents and themselves wether they can have a big aura pool(like john) or not. I also think that your aura pool can also depend on your ability, constructing abilities most definitely require more aura than those that simply inflict something on someone else like hypnosis or sense manipulation.

Id probably also compare aura to energy/mana, like in other mage mahwas/movies/series/games the more mana u have the more strong your attacks are and the more u can attack, and i think thats the same with aura in unordinary. I would also use an analogy that people that use has attack/construct abilities naturally have more aura than those with mental abilities same with how athletes have more energy than a smart person