User blog comment:Jartsa67/question about souls/@comment-11331875-20130829165332/@comment-1509826-20130829190334

As far as I gathered, the indication wasn't she made the colt work, the colt still worked, she just managed to create some more bullets to fire from it, as it was stated, it took both the bullets and the colt to make it kill everything. Ruby somehow managed to make more bullets, presumably like you said through heavy-duty witchcraft. As they've lost the colt, Bobby can't really do much about it, because without the gun, the bullets are useless.

Interesting theory, although it does beg the question why can't they be resurected? (Lucifer can resurect them sure, but he's the fourth most powerful being in existance, he can do just about everything.) I always assumed, that when a soul was battered the point of no return, it stopped being a soul and became a demon, as it was now a demon rather than a soul, it ment it could be killed. Its a common use in fiction, that some things are imposible to kill, but its not impossible for them to be changed into something that can be killed.

I agree, the knife will kill the host, after all a knife wound to the chest will kill an ordinary man. However it clearly can't destroy souls, or else it wouldn't only work on demons.