I've had acupuncture done on my horse and he LOVED it! He went to sleep and went to his 'happy place.'
I'm a total believer in it.
It won't help a horse become less fearful, but it can help with pain. And if the horse is reacting fearfully or spookish because of pain, then it may diminish. But if the horse is fearful of an object, different environment, etc. then it will not cause the horse to be more brave.