Block from (Holy) Sheltron just feels awful, because you already get block via rng anyway.
Every time I use it I'm thinking "I might have blocked that anyway" so the skill feels borderline useless.

Compared to other tanks where it's a 100% additional 10-20% mitigation.

Then there's the Oath gauge, meaning you don't even have your on demand mitigation tool available unless you've hit the required number of physical GCDs.

As for the rotation, I've leveled to 89 now and I still don't understand it.
I get that you have three priorities, your Royal-Atonement combo, your Goring DoT combo, and you magic combo. But these don't have an intuitive order to them and don't seem to line up. You want your physicals during FoF which is obvious enough, but what about Goring? It's duration is pitiful so do I aim for 100% uptime or what?
By trying to feel it out logically, it seems like it should be Goring > Atonement > Goring > Atonement > Requiescat > Repeat. But that doesn't quite line up (Req ends up with 3-5s left on the CD by the time I'm ready for it) and it comes with the paradox of "do I open with my DoT or with the magic combo to make the most out of MP as a resource?"

Nothing about this rotation makes any logical, intuitive sense.
GNB on the other hand clicked instantly and always feels satisfying as every single cooldown gets hit on milisecond it's available again.