The article’s comment on armor should have gone through Clements too. He might have clarified a little bit.
NO sword could cut through articulated plate armor, doesn’t matter if it’s a Japanese Dai To or a European longsword. The masters tell us that when facing an armored opponent, you should use the point against the weaknesses of the armor. The visor, the arm pits, the back of the knees, the sole of the feet, the palm of the hands and anywhere were there was articulation. Now, for that purpose, yes, the European longsword was a better fit. But this has nothing to do with it’s cutting ability and certainly not with it’s weight. In fact the European longsword would (on average) have weighed less than a katana per unit of length. This has to do with differences in blade geometry. The end result is that the (typically) shorter katana weighed the same as a (typically) longer European longsword.
As for what would make a great sword? I think those guys got it right. We’d be hard pressed to beat the ~3 pound 48 inch steel longsword.