Tknife, if a lightsabre only severed 6 of the ropes, either they are reinforced, its a rip-off, or who was ever using it simply forgot to turn it on. Mine can cut a freehanding railroad spike and only produces a 5 angle arc on the remaining piece. Note however, I have narrowed the beam on mine after consulting with Joe Talmadge to give better slicing performance. A standard version would produce a bigger arc but will still cut the spike. A LucasSabre (TM) will send the remaining uncut peice of iron swinging and if you are close to it, it will wrap completely around whatever you have it tied on and smack you in the back of the head (speaking from experience).
-Cliff