Generally speaking, when an animal awakens, it gets a brand new name, and usually some nifty abilities....
Like the awakened chicken, that turns people to stone... (aka the cockitrace)
Or the fire breathing dog (hell hound)
Or the acid dripping dog (cerebrus hound)
The only awakened horse I know of is the Nightmare.... but he doesn't want that trust me. The nightmare instills a compulsion into its victums to ride it, where it gets stuck in a natural adhiesive on its back... the Nightmare then swims out to sea, drowning its rider, and eats him. (Yep. The Nightmare is a man eating, swimming horse!)
As for barding.... yea.... NO idea at all. Depending on the armor (what he wants it made out of, to look like, etc) easily 10,000 to 150,000.
Remember, the you're not running down to the corner store to buy this stuff, it has to be custom fitted and crafted.
It did a quick internet search and found a couple of sites.... one offered "decorative leather barding- head, chest, rump" for $750us. 60 days to make.... and would protect shit all. (It was a few straps of leather that covered the chest, head, rump, covering about 15% of the animal while leaving huge (12 to 20 inch) gaps everywhere! (Making it basically equal to you wearing oven mits and calling it full body armor!)
Seriously, the stuff wouldn't stop any weapon from hurting the horse! But it was pretty!