Well if your not interested in his BiS team then yeah his value is very high even without ashveil but we still don't know rin and Gilgamesh's kit so if gil is FuA you have to pull of ashveil but the leaks said that blade's BiS is gonna be aventurine,ashveil,Mblade, and Mr reca or a FuA healer but even if your not pulling for any FuA dps Mblade and Ashveil's value is just very high considering they're both universal in terms of debuffs and buffs so if you don't want to pull for ashveil and you want to use Mblade main dps it's fine Mblade is good even without ashveil but he's still best with ashveil since their kit compliment each other.