I'll be kinda brief in my responses to these suggestions:

PLD

- oGCD stances should never be a thing for DRK/PLD IMO. What I'd prefer is to give them extra, stance-specific effects on certain skills instead. DRK has this currently with Grit-Souleater (even then it's not that impressive, however) so a move in that direction would help differentiate things between the 3 tanks.

- Sheltron just needs to provide TP, period. Just seems odd that a physical only CD doesn't provide a physical based resource, but magic instead.

- Wouldn't mind Clemency being oGCD (not with the TP gain though, too similar to Equilibrium). Flash and CoS changes... eh. Would rather just see Flash do damage instead if it came to it. Nothing major (like 50pot or something) but enough to aid PLD in AOE situations a bit more.

- Veil suggestion is cool, no harm there I guess.

DRK

- Co-sign having DA DD increase parry rate.

- An AoE silence? No, the blind effect is fine. Besides even if you made it a silence, no DRK would waste MP on it when other silence users can do theirs for free.

- MP refresh how? Like Blood Price or Shroud/LA? Either way Shadow Wall does need something more than being a Sentinel-lite. Not sure if this suggestion is the answer though.

- There has to be some kind of trade off for making BW available under Grit. Keeping it as is would probably make the Job broken.

- Do DRK even have TP issues for Sole Surivor to get changed like this? Yes WAR getting a mini Invigorate was silly but you can't use that as reasoning to give another Job something it doesn't need.

In conclusion, these suggestions give me the impression that you just want DRK/PLD to be another flavour of WAR, instead of emphasising their own individual elements to make them stand out more. I get that this is your wishlist of what you'd want, but it nonetheless suffers from the same problems these kind of threads get: it doesn't address the things that should be changed, but simply what you want changed, because reasons.