Hello Hello! Mekella here to help you understand the rankings of which will be discussed in the World's End Arc!
Starting from Strongest to Weakest!
•SSS Rank (Those who possess powers of the gods, or have reached just barely below it. Can usually borrower powers from the gods if they have a strong enough connection to them.)
•SS Rank (Students who have achieved power that can be labeled as divine but isn't necessarily divine in any way. Ex: Magic capability, Speed enhancement, strength enhancements, time manipulation, etc)
•S Rank (Those gifted with extreme magic capabilities that can be used in most ways. Freezing magic, fire, earth, etc.)
•A Rank (Can use some forms of magic and has some sort of power. Usually only gifted with one way to use magic.)
•B Rank (Usually only Can use spells to help but not capable of utilizing magic to its fullest.)
•C Rank (Typically the student listed as C Rank is capable of great swordsmanship, martial arts, etc. Not really strong magic wise. But can learn to counter it.)
•D Rank (Those who have awakened power but haven't really figured out how to use it or if its even useful. Still can learn magic or different fighting techniques.)