I think it'd be a good idea for sunetted weapons to have a limit breaking mechanic. There could be a somewhat rare/hard-to-earn item that would allow players to update it one season at a time depending on that season's power level capacity. That way, there could be more of an incentive to grind, the loot pool could be slightly bigger, newly introduced gear could serve as an easier option, and players would be able to at least have to put in effort to keep their favorite weapons updated.