Seriously, there is no good reason why this shouldn't be happening.
Every other costume set has Damage Bonus on both the Helm and the Armor. Whether they be low or medium separately to make Medium or Very High altogether, why not the Divine Mantle?
My suggestion? Move half of the Damage Bonus from the Divine Veil onto the Divine Mantle so both the Divine Veil and Mantle can have a combined Damage Bonus vs Fiend Medium.
Whether it be intended or not, there's an unbalance between the Veil and Mantle which would make people chose the Veil over the Mantle.
It's like the Deadshot Chapeau set. There's a Medium undead Damage Bonus to the Deadshot Chapeau and the Deadshot Mantle. You wouldn't be loosing out on either bonus because both the Chapeau and Mantle have both the Medium Damage bonus.
Practically EVERY OTHER ARMOR SET has a SPLIT DAMAGE BONUS of either Low or Medium. The Divine set? It doesn't. But it really should.
I think that's becuase it's one of thse special armors. most dual defense are like that. Think; Divine has a armor that is less effective, so consider it only a helm. what armor set has only a body? silvermail. Combinde set's;
50% shadow defense, 25% elemental, 25% peircing. Damage bonuses vs undead and feind, both inflict and ressist shadow. Covers up all the weaknesses a shadow weapon would have. Plus, you get full curse ressist, so it's like a gran faust buff.
Also, didn't divine veil used to not have shock ressist?
Was missing bonus even intended or not? If its supposed to be there, I'd rather they just correct it then split the bonus into 2 half-bonuses.