Small temporary fix for Nocturnal Sect IMO :

1. Change Time dilation in nocturnal sect to Enhanced buff instead of Extend buff that we have now(but let it be the same under Diurnal). Of course, this effect will work also with our shield from Aspected Skill(so a 2000 damage barrier applied to the party member become 3000 damage barrier after Time Dilation is applied to said party member)
2. Change Celestial Opposition in nocturnal sect to have same effect to Time Dilation above, albeit in reduced potency increase(maybe around 15%, 25% or 50% increase just like current Celestial Opposition is 33% of current Time Dilation, 5s increase to 15s increase) to party.

Just these 2 change will give us comparable(more reliable, but weaker) shield than SCH. Of course, SCH can still bring a lot more utility to the team(more Single target DPS, fairy regen, the slightly OP Indomitability, 3 Lustrates in a row, incomparable MP management, etc), but a Nocturnal Sect AST will become viable instead of their useless condition currently.