Why do they use knives for decapitation? It seems a little labor intensive for the job, when a nice heavy sword or broadax would be easier and quicker. Or is that the idea?
Maybe the procedure is in the Koran.
I think that's the idea.
If you'd have seen the videos, you'd know that they like to take their time and even like to make the victim help by 'assuming the position'. Sounds like this guy's decapitation was faster than average.