That's a good thing to know about the cigarette lighter! Quicker and easier than a soldering iron and a lot safer as well.There's almost always a bully in the group. Some folks have had success removing the bully from the flock to a separate area for a few days or a week.
Re-introduction to the flock can put that bird at the bottom of the pecking order. Sometimes it works, sometimes it does not. I've used Pick-No-More lotion deters pickers because it is spicy and birds don't like the taste. Some people have claimed success with dog sprays like Bitter Apple or Phooey! I had an extreme case of a nasty hen injuring other birds once. I took her out to the truck, took a car cigarette lighter and carefully burnt the top section of the beak back 1/8". The bird didn't suffer at all, but the beak was sensitive for awhile and quit picking other birds. It didn't stop her from eating and drinking either. I recommend trying the anti-pick lotion. If that doesn't deter the picking, separate the bird for awhile and re-introduce.