Cull her. Don't take chances with neurotic behavior. Some birds have OCD, basically. It's not always a boredom or nutritional thing, and even if it is in some instances, bad habits are hard to train out (when it's possible at all), you don't want her weak genes messing up your breeding lines or ruining morale for your other layers.
I haven't seen it as much in Leghorns, but I did see it a hatchery Australorp. She went crazy for blood and picked at every injury she saw--including picking human scabs and wounds.
The Blu-kote spray can work, so always try it if you have a bird with blood frenzy. Feather picking can sometimes be helped by sticking molted feathers out. You can try switching them to a diet higher in protein. You can try Peepers/chicken blinders. But from the sounds of it, you've tried most of this, and nothing's worked, so I'd cull her if you don't want to sell her. She sounds more neurotic than simply nutritionally deprived.
Also, even if an illness or condition might be treated, there isn't necessarily a good reason to do it because by training this one and constantly working with her, you're ensuring that you'll get more of these defects in your flock. Why not spend the same time and resources on easier-going, healthier birds who don't make you or each other miserable?
I phased them out after a while, but that seller's photo of nice blue eggs caught my eye. I wonder how true to life that photo is. I started to think an hour drive up to Lafayette to see in person might be worthwhile. Then I came back to reality and reminded myself I have too many other current chicken plans right now. 
