Fire and Shadow resist rarely mix

Looking at the Wiki, I discovered that an armor set that has Shadow resist nearly always have resist penalty of fire (Angelic line and Skelly line). The only exception are Silvermail which has no penalty, Fallen and Divine set which has a bonus.

It appears that a very high priority design goal that OOO had for the game was that everything *MUST* suck in at least one critical way, usually more than one.
The divine veil does shadow damage, has protection against fire and a damage bonus against fiends! But, it sucks because it doesn't have normal damage defense.

it has a penalty against fiend
Which is irrelevant and a minor hindrance at most.

Then you suddenly realize that T3 Fiends being spawned in a small hallway with agro on you and weakeness to fiend is very, VERY bad.
You don't take more damage, you GIVE less damage. Derp harder.

Damage penalty vs Fiends Very High isn't a minor hinderance, and it's incredibly relevant since this protects against shadow, which is why you would be using this armor for Fiend and Undead themed strata in the first place.
You should also look in the Deadshot direction, it gives a bonus damage to Undead Very High and doesn't have a negative fire resistance. Not very many people know this, but armors with natural fire resistance are equal to low fire resistance UVs a piece, so getting a fire resist UV will solve that issue.

Damage penalty vs Fiends Very High isn't a minor hinderance
You do maybe 20-30 less damage on a normal attack. It's not that big of a deal.

Funny, people will pay quite a bit more for a weapon with a UV of increased damage against fiends medium, and a lot more for very high. But, you brush aside the penalty. Hmmm. I've seen you do brush aside the penalty in other threads too, but I've never seen you brush aside the UVs.
I've have both a fallen and a divine piece, and I notice the difference when devilites/wings/greavers show up when I'm not expecting them.
I agree that the penalty on the fallen line doesn't make it unusable, but I don't wear mine as much anymore now that I have more 4*/5* choices to play with.

But, you brush aside the penalty. Hmmm. I've seen you do brush aside the penalty in other threads too, but I've never seen you brush aside the UVs.
I don't get your drift.

"It appears that a very high priority design goal that OOO had for the game was that everything *MUST* suck in at least one critical way, usually more than one.
The divine veil does shadow damage, has protection against fire and a damage bonus against fiends! But, it sucks because it doesn't have normal damage defense."
Vog Cub doesn't suck in any way, in fact it's kind of OP. Which is why more than half the people with 5* gear use it. Or would you say everything OTHER than Vog Cub is underpowered instead?
Vog Cub + Silvermail all you need baby. ;-)

Vog Cub doesn't suck in any way, in fact it's kind of OP.
The vog cub sucks because it doesn't provide any other resistances other than fire, while other kinds of armor do. It sucks that it leaves gaping holes in shadow/piercing defense. It sucks because it does nothing for your bombs/guns. It sucks because it has no damage bonuses against any kind of monster or for any weapon. It sucks because the ASI isn't as useful for fast swords.
Yes, the more popular equipment tend to suck less for the play style of the majority of players, but they still suck in important ways.
Vog Cub + Silvermail all you need baby.
Unless you never ever make a mistake and get hit, that combination doesn't provide enough fire protection (especially for the FSC), it doesn't provide enough normal protection, it does nothing for shock, it won't help you swing the DA/GF faster, etc. In short, it sucks in important ways.
Crown of the Fallen is awesome.