Comments of chapter undefined of The Overpowered Gamer (Harry Potter)

here's an idea a perfect way to use the "Christmas skill" would be to create a Sub-Class skill. You can balance it out by having the sub-class equipped only provide a certain percentage of the stats and reduced effectiveness of class abilities/skills it would have when equipped as the primary class while also reducing the XP of both classes by splitting it between the two(a debuff basically for the sub-class's basic stats and linked skills/abilities to let's say 40% normal state/effectiveness and splitting XP gains 65% to the primary and 35% to the Sub-class). It would still be OP if you had your highest level class equipped as the sub class.