AST's nerf goes too far.

[Nalien]

especially since PvP was the only place where you could use Nocturnal Sect with it actually being better than Diurnal.

Honestly, I don't think Nocturnal should ever have been an Adloquium clone in the first place, it made more sense to me for it to be closer to Phalanx in XI; An effect which reduces damage taken by a value (rather than a percentage, which is what we have with tank skills). A shield simply never correlated well with abilities like Time Dilation and I've always discredited Nocturnal on that fact alone. Diurnal gives Regen, and extending the duration of Regen is extra HP restored. Were Nocturnal closer to Phalanx, I'm not sure how it would balance compared to Regen, but it would at least benefit from increasing the duration, not to mention stack nicely with Stoneskin/Adloquium.

Lets say, on average (in PvE), you'd take 10 hits in 30 seconds while taking (pulling that out my rear for simplicities sake). Currently a ~2,000HP Aspected Benefic will shield ~2,600HP. Lets instead make it like Phalanx, and it now mitigates ~260HP per hit over its 30 second duration. Since you're taking 10 hits over that time, it mitigates 2,600HP, but now Time Dilation can extend its duration. If someone is going to take more than 10 hits in those 30 seconds (which seems fairly relevant to PvP), it is technically doing more for you. They can even make Aspected Benefic and Aspected Helios stack for Nocturnal Sect in that regard.

It wouldn't be particularly hard to balance, and it would be far more interesting than effectively cloning Scholars thing. As far as PvP goes, it wouldn't be stupidly overpowered as is currently the case, instead it could potentially be a fairly useful status effect to have. Sort of like another form of Testudo, but not percentage based. Every hit you take it would be mitigating some damage, when people are running into a group that would be fairly nice. Only issue I can perhaps think of is auto-attack damage perhaps being entirely mitigated by a Phalanx style effect, though even that isn't too hard to balance out.