As stated before, the Defiant Armor/Shield enchant rules state that
"Armor and shields with this special ability excel at blocking the attacks of certain types of creatures, similar to a bane weapon's excelling against certain foes..."
As there is a Mythic Bane ability for weapons, would it not be unreasonable to have a "Mythic Defiant" shield/armor where the "designated foe" in this case are mythic creatures?
or would it have to be chosen as part of a subtype? (Mythic humanoids, Mythic outsiders, etc)