Speaking of which, and this is totally wording things up, but what it says is:
"When you take damage from an enemy of higher level..." then Defy Danger.
It also says:
"Armor - The item subtracts this amount each time the wearer takes damage."
Semantics, of course, but does that mean that, having soaked that one crushing point of damage with my plate mail, I now have to Defy Danger, even though I lost no HPs?
Is "taking damage" different from "losing HPs"?
I realize that I don't have to jump through hoops to justify this, because you're the designer and probably knew what you meant.
So, after wasting all of that typing, "Might you Defy Danger from a damaging attack, even if none of that damage gets through?"