My father has a horse that sounds somewhat similar. But the horse isn't high-strung at all - in fact, I think if he'd been handled properly from a young age, he'd probably be a great kid's horse. He's very good under saddle.
My dad got him from a horse dealer, so we don't know who owned him previously. My dad thinks he was abused, and he's not someone who always jumps to that conclusion. The horse also a pain with the farrier, and if he's ever in a situation he doesn't like on the ground, he'll fight you (I personally think he may have been allowed to get away with a lot at some point as well).
This guy isn't as severe as your horse, but that's probably partly due to temperament. He is a naturally laid back horse, I think. Anyway, I would say try not to feel sorry for the horse and be firm, but fair. This has been my dad's approach and the horse has improved quite a bit. And when you're doing something he doesn't like, be quick as possible.
For example, with the dewormer, I have the same issue with this horse. I always get someone to hold him and tell them not to stand in front of him because he has tried to strike us. I squirt that dewormer in his mouth super quickly, and it's done before he has time to freak. Then I give him a bit of oats and he forgets all about it.
The applesauce is probably a good idea, too. I've done that with younger horses.
Buck Brannaman might be a good person to check out, too.