WotLK [Guide] [PvE] A comprehensive guide to Protection Paladins

Why not Aura Mastery for Prot Paladin?
I've been looking at many guides for Prot Paladin recently and almost all of them say unanimously to spec into Prot / ret talents and take zero points into the Holy tree.

However, on the private server that I play the consensus is completely opposite in that for end game raiding like ICC25 HC and RS 25HC you want to have Aura Mastery. I guess for fights like Sindy, LK, and Halion it's useful for abilities where you would want more magic resist and an extra cool down?

I'm by no means an experienced tank, and I definitely feel like for trash pulling Seal of Command would be really amazing, and I do like pursuit of justice but I don't really know of it's really necessary (do bosses even disarm us? If I have nitro boots do I really need pursuit?). I guess my question is why is it wrong to go down the holy tree?

If my threat on bosses isn't that bad or lacking wouldn't the extra CD be better then more threat generation? Should I really be worried about missing out on Seal of Command for trash? For what fights and specifically what abilities of bosses would you want AM over more threat?

I have a couple other questions like at what point should you go for 4 piece tier set over more armour. How much armour is too much? Would more stamina be better for ardent defender?

What abilities you need to worry about for tanking in ICC and Halion. How much expertise do you need for Halion. Is blade ward actually useless and if so which enchant to use on weapons?

Do I need judgements of the just? What about vindication? It seems like both of these can be covered by other classes but what about for fights where you don't have those classes? Would it be better to include these for 10 man HCs? Or in case you are missing the other classes? Like what about Halion where he can party reset? It seems like you would want to have judgements of the just to reduce the attack speed by 20%.

I appreciate you taking the time to read this. Of you think there is another place to post this please let me know and I'll direct my questions there.