In the movie “The Bodyguard” Kevin Costner dropped a very shear scarf onto a sword blade where it was cut in half by its own weight. Is this physically possible? I know about Japanese standards for measuring sharpness using straw bundles and (in days gone by) bodies, but we are dealing with an object of very little mass in this case. If you have seen the movie you’ll know what I mean.
The blades steal things to get sharp?
∆ I’m with supid. 
I saw the STUPID mistake as soon as I posted it. Unfortunately, I could not get back in to edit it. I clicked on the "edit " button and I was told that I do not have permission to edit my own post.
Okay. Based on steel rather than steal you get to the question as to how do you define sharp. Cutting power is essentially an expression of the force behind the blade divided by the area of contact. Based on this is comes down to how much you can grind down the blade (what the tip radius of curvature is). This will be in some controlled by the grain size of the steel and how prone the steel is to oxidation. Anyway, we get back to the q of how to define sharpness.
Apparently not as sharp as obsidian or flint.
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I don’t think there’s anyway possible for a floating scarf to cut itself in two by more or less floating onto a steel blade regardless of how sharp you tried to make it. It’s just more Samauri Sword Madness.
While not exactly historical fact there is a scene in the * The Talisman * by Sir Walter Scott where King Richard and Saladin are having a parlay and begin discussing the merits of their respective weaponry. To demonstrate the strength of his sword King Richard cuts the iron handle of a mace neatly in two with one powerful blow. Saladin then demonstrates the sharpness of his blade, a Damascus steel scimitar, by first cutting a soft cushion in two with just the weight of the blade, then by tossing a silk viel in the air and deftly slicing in two with his blade. Not quite the same as letting it drop but also more plausible.
Read the scene for yourself online
I doubt very much if it’s even close to possible.
Just after the movie was first released a bunch of us decided to test this story using a steel microtome blade. Those things are sharp. About as sharp as sharpened steel can get. Sharpened on carborundum, then glass then leather. Like, really sharp for steel. And really high grade steel. Far better for taking an edge than metal that has been designed to take the impact of being swung into bone.
Anyway, we got one of these blade, about 8 inches long, and we dropped a normal peice of cotton material onto it (it was actually a pocket torn off a lab coat). It didn’t cut. Admittedly a little smaller than a handkercheif, but cotton is much denser as well.
Then we tied some bulldog clips to the cotton and started adding the calibration weights form the balances. I can’t remember exactly when it finally gave, but it didn’t even begin to cut until we had more than 200 grams of weight on the thing.
Admittedly anecdotal, but it convinced me that the story is bunk. Steel just won’t easily cut cloth without some sawing motion to break the fibres. There’s just not enough weight on any individual fibre to shear it otherwise.
Maybe swinging a curved scimita at a peice of loating cloth would cut it because some sawing motion is induced. Simply letting cloth fall onto metal doesn’t work.
Your test confirmed what I always thought to be true. Thanks for including all the specs. This was more a question of physics than swords.