As the small group of mercenaries settled down for the night, they failed to notice that some small pieces of barbed wire sticking out of the ground nearby were moving like tentacles.Until it was too late and they woke to feel it clutched around their throats and squeezing hard. As their blood spilled upon the ground the Barbed Arms had claimed yet more victims.
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.