Just letting them level up with use to unlock kill tracking and orb generation would be enough. They shouldn't tie that stuff to catalysts. Unpopular opinion but I feel catalysts, when done right, should never launch with the weapon. Catalysts like the rat king and trinity ghoul are great to bring life back to an aged exotic. Maybe one day they'll go the borderlands route and have random rolls on exotics while keeping their perks. This could make getting drops you already have rewarding . They would have to fix collections first.