Ch 0.1: Grades in JJk
Following rankings are used to classify jujutsu sorcerers, cursed spirits, cursed tools and cursed objects in general, with grade 4 being the weakest.
Grade 4
Grade 3
Semi-Gradde 2
Grade 2
Semi-Grade 1
Grade 1
Special Grade 1
Special Grade
Grade 1 is the peak of most of the sorcerers in Jujutsu Kaisen, Special Grade Sorcerors are the ones who are overpowered beings.
Most of the Powerful Cursed Tools, we see in anime are Special Grade, which have a technique within them.
Rest are just used by sorceroes for asistance and to increase their lethality.
Curse Spirits of Grade 3 and Grade 4 are very weak existence and can be killed easily.
But above them, the curse spirits gain sanity, so it is much harder to kill them.
Some of them might even have powerful curse teachniques, starting from Semi-Grade 1.
There are only four special grade sorcerers in Jujutsu Kaisen, who are,
Yuki Tsukumo
Suguru Geto
Satoru Gojo
Yuta Okkotsu
(Sukuna and Kenjaku belong to old era)
Weekly Power Status
-- Power
Ranking 
-- Power
stone