If he’s that
aggressive/non-influenced by pain, I’d suggest having your/a trainer work with him
exclusively for 30 days (or longer, if need be) so that he learns respect. If, after that,
you can work with him safely, then keep/sell him as you like.
I can tell you one thing,
though, selling a horse that can’t be worked with is nearly impossible. Hell, giving away a
horse like that is nearly impossible.
My filly “attacked” me and kicked me in the chin,
but she was also 4 months old, had known me for a week, and I’d been giving her shots that
entire week. She is pig-headed sometimes, and is totally unflappable, but I know that if I
actually hit her with a whip, esp. on/near her head, she’d
definitely pay attention and back off. She mainly likes testing the boundaries, rather than
actually trying to cause harm/be dominant. (And, she’s 3, so she hasn’t quite learned how
to safely test boundaries…i.e. she’ll break the cross-ties by twisting around b/c she’s
bored, or she’ll pull me a few steps while lunging as she tries to go faster/farther,
etc…nothing dangerous).
Anyway, I’d suggest professional training for him, and/or give
him to a professional trainer if you don’t want to put in the time/money. He’s learned the
art of intimidation/harm, and you likely won’t be able to un-learn that for him…a trainer
might, or might not, but at least they’re getting paid (in some form, either by you or by
his future sale price) to take that risk.