What you were expecting to happen, and what actually happened?
I expected Aspect of Humility to fire whenever he took dmg, instead it only activated when dmg was dealt to his life.
What are the steps to make it happen again?
Start a game, take skull dmg to your armor total, no 3rd trait. 
Do you have any screenshots or video you want to share with us so we can see the problem? Attach them to your post!
No
Humility’s trait triggers on the same conditions as Frenzy does, so yes, it’s expected that only reduction in Life will trigger it.
If this is how you intend it to function, then please change wording to read:
All allies gain 2 Armor and Magic when I lose life.
But I would prefer if it just activated at any dmg taken to be honest. 
I never took notice of frenzy. I was really excited about Humility though…
This is sad, but not a deal breaker.
If Armor is the only stat hit, then you technically weren’t damaged.
This is basically the definition of armor.
While I understand the functionality of armor AND the logic behind the non-firing of the trait,
because of the use of the term “DAMAGE” in this game, the wording for this and ANY OTHER trait that only fires on life dmg needs to be changed.
War and Peace says it deals X dmg… it applies to armor first. By the definition of “Damage” above, it should be ignoring armor because it says DAMAGE.
It is a matter of syntax and semantics. I just felt the trait was misleading as is. My troop took damage, it was just to his armor. So it should have fired. If it reads, when I lose life, then there is NO confusion.
Two more cents from me…