Class mods in Borderlands 3 have a name or suffix that will note the skills given by the class mod. Skills that are boosted by class mods will also be shown in the skill tree selection, listing the number of bonus points from the mod and the final percentages for the skill. It is possible to get up to 3 different skills boosted by a class mod.
The rarity of a class mod determines how many skill bonuses are given:
White - 1 skill bonus
Green - 2 skill bonuses
Blue - 3 skill bonuses
Epic - 5 skill bonuses
Legendary - 5 skill bonuses
These skill bonuses are split, such that the full bonus can't be on just one skill. The splits for each rarity target the 3 possible skills and looks like this:
White - +1.
Green - +1/+1 or +2.
Blue - +1/+1/+1, +1/+2 or +3.
Epic - +1/+2/+2, +2/+3, +1/+1/+3, +1/+4, or +5.
Legendary - +1/+2/+2, +2/+3, +1/+1/+3, +1/+4, or +5.
Apart from the legendary variety, class mods exist in all rarities varying in skill bonuses and affected variables.