This skill should be straight forward:
If you control a petit moth equipped with cocoon of evolution you can send them to graveyard to special summon a moth monster from you hand, field or graveyard. On your 6th turn and onwards you can special summon up to 2 moth monsters with different names. You can use this effect twice per duel.
Not exactly since you have to offer 2 cards first. So is bassically 2 useless vanilla monsters for 1 or 2 big fat vanilla monsters. Imo a fair trade. Despite that it would still be a mediocre skill since you will need to run a deck full of bricky/useless cards like the moths/cocoons. But at least it wont be a terribad skill as it is atm.