I am not sure this is correct. When you strike someone with a sword you only strike with a small area in any event, so unless you are using the sword like a saw that is not really an issue. The sharpness of the blade is the key "smallness" not the length.
If I remember correctly (and I hope so 'cause Brian will be testing me on this soon) a well make blade has two nodes or points where the blade does not vibrate when struck so that if the target is struck at this point on the blade, the maximum amount of force is transmitted to the target. In a well made blade I understand that the second node is in the pommel so that the hand does not have to deal with any more vibration that is absolutely nec.
I would guess it would be easier to lop off an arm with a two handed sword than a small blade like a scimitar, but I have not had an opportunity to figure this out yet.
For those who are interested in these things AEMMA (which Brian runs at the same location as TAC) will be having an open house this Sat from 12-2. There will be tack stuff, sharp edged cutting with swords, armoured combat and a number of martial arts activities going on.