What is horse getting fed? It could be that feed is too hot, hay included in that, and horse would chill out somewhat with a change in feed.
And has any blood work been done to rule out hormonal problems?
Eyesight is good idea too.
And there is a chance trainers had success with stopping this at their barn but you might not have like their methods, so they just said they had no luck? Not saying 'tis so, but possibility unless you were there to see horse had not changed.
Irregardless, I'm with Herdbound on this, if CBC/vet check of eyes and ruling out brain tumor and such, and also dental exam, doesn't pinpoint anything, I would probably PTS.
But also want to inquire as to your handling mechanics. Does this horse do this with everyone, or are you the only one handling it at your place? Are you exhibiting timid behavior around this horse in any fashion? Is it only the two times then that he acts like this?
I would not lean towards abuse as being root of this, but question whether he has "learned" he can get by with this behavior only when in stall or cross tied, either because the "intruder" leaves the stall after hanging bucket or feeding and horse thinks it has run person off, and because when acts like this on cross ties people are usually preoccupied and ignore it, or they startle or avoid him.
A lot of how a horse reacts to correction is in the force, is you will, of the person who is correcting it. And don't mean how physically strong person is per se, but how strong a person is in their mindset and physical attitude.
You probably know the type I mean here, same type you hear in grocery store telling obnoxious offspring, "quit that, I'm telling you to quit, stop it right now" over and over, while the kids do whatever they want. Whiny voice, sweety voice, but mainly weak voice. Kids and horses in this case, know there is no backbone to it, and carry on however they want to.
It could also be horse is getting rewarded, because no one is calling its bluff, and getting after it strongly enough too. If horse were really aggressive, I feel it would be turning rump to you and letting you have it, instead of doing what it is.
Has the horse ever come after you? Or just does what you have described?
I really feel this horse needs a CTJM more than anything. I'd stick him on the crossties, and be prepared to leave him there for a couple of hours if necessary, meanwhile I would walk past him and around him with carrying everything but the kitchen sink.
And if you are one of those, that talks soothingly? As in "it's all riggghhhhhtttt" or "don't be like thattttttt"? Quit it. Horses don't respond well to that, and it makes many a problem horse where there wasn't one to begin with. And also talking to the horse, when it is misbehaving other than in a tone that is matter of factly stern, also should not occur.
And curious too, as this just occurred to me, you didn't say horse also does this when you go to halter it, so horse obviously knows how to behave?
I really think the horse has one over on you, either because of your body mechanics, which are somehow expressing timidity, or because horse is getting rewarded with sweet talk or soothing talk possibly.
Also is this horse getting turn out time? Not just a little, but a couple of hours or more. Might have something to do with being stir crazy from being stalled much of life, if that is case.
Also, what type of horses, if any are on other side of him, as I've seen some horses cut up worse, when horses on either side are less dominant, but if boss horse is stalled next to them, they are quieter.
I also don't think abuse is behind this, but rather a horse that has learned he can do this and get away with it.
Horses make me a better person.