Darkness nested in the woman’s heart
And her husband found that the Dark Face lingered there
So he took her to a pit of fire
And he cast her in.
-Twenty-Ninth Explanation, Sun’s Sword 5:8, The Book of Two Faces
The God has two faces, and wears two masks.
One is a bright mask, shining with light, shining like the sun’s gold; it is the Gold Mask.
The other is a dark mask, blackened with shadows, black like the night. That is the Dark Mask.
-First Explanation, Priest’s Teachings 1:2, The Book of Two Faces
Expansion from the Horse Brass item: Specific Armor charms.
Cooling Touch Charm: protects horse against extreme heat, and fire, magical and mundane
Jove's Favor: tin charm shaped by a lightning bolt that protects a horse primarily from natural lightning, but also potentially from lightning based attacks. In real life, lightning kills quite a few horses and cattle a year.
Hermes' Blessing: gold charm that grants the horse magic resistance, and perhaps immunity to cantrip level magics.
Vulcan's Steed: This large iron charm in epic fashion renders the steed invulnerable to iron weapons. Such things clatter off of the animal's hide like twigs.