Find the official wiki here with all necesairy info.
Every Class Armor bundle has it's own project page as well :
BMA : Berserker, Mage and Archer :
https://minecraft.curseforge.com/projects/class-armor-berserker-mage-and-archer
UmbraLux : Necromancer and Paladin
https://minecraft.curseforge.com/projects/class-armor-necromancer-and-paladin
Beastmaster
https://minecraft.curseforge.com/projects/class-armor-beast-master
In short :
Find a new Inventory in this mod to add a bunch of nice jewelry to your body, and let its magic affect your powers !
Extra exp, attack boosts, debuf rings and many more.
ClassArmors add sets of armors, included with shields and weapons that allow for nice special attacks like the AoE Hammer Smash (Berserker) or Torment of Fire (Paladin), or have fun with your very own, unique wand, and throw spells at people by typing them in the chat bar !
All require the SubLib to run.