The "hook" on the tip is what carries the cutting edge. That way you can draw the blade up the stomach the same way you would use a rescue hook. The skin is slit open but the intestines underneath are unscathed. As Brian says, less messy that way.

They are certaintly not necessary to field dress an animal; I used an Old Timer Woodsman with a 5" drop point blade for years. But they are a little more forgiving when you make a mistake.

Regards, Vince