I added this to provide a clearer idea of the rank progression. For those who read the chapters before I made the edits, this will save you from needing to go back and re-read everything. Eventually, when Nate progresses enough this will be how his strength is quantified instead of levels. This will be updated as the lore progresses. 

Humans

Humans are exact in quantifying their strength by dividing between core and physique:

Mana/martial core stages-

Initiate, Novice, Apprentice, Adept, Expert, Elite, Master, Grandmaster, Champion, and Ascendant

Physique-

mortal, enhanced mortal, exalted, ascended, celestial, demi-divine, divine, immortal, transcendent, and god

Demon 

The demon race uses a combination of core and physique to determine their power levels:

Low, mid, high, royal, and transcendent with each having four tier's low, mid, high, and peak 

Example: high-tier, Low-rank demon

Beast

common, uncommon, rare, elite, legendary, ancient, celestial, abysmal, primordial, and godly