I'm incredibly novice, and I did this a couple of days ago, but I remember while sort've reverse-engineering things, I noticed that sacrifice flesh was both a shout AND a potion effect. I also believe it may have been a status.
My editor is currently crashing at the moment, so I can't check for you (I tried :P), but you may need to modify all 3 to reference each other where appropriate, to make your skill work.
