There's width, and length, but don't forget thickness.
And most pictures tend to have difficulty showing the thickness of the blade, most especially how much they thin along its length, and that makes a big difference.
Japanese swords typically got a tad bit thinner as you went down its length, but not by a whole lot (maybe ~70-80% or so thickness at the far end before the bevel); and many examples hardly at all. Western/middle eastern blades tended to thin out much much more as you went down its length (to ~40/50% thickness at the far end). (And for comparison, Chinese blades typically had little to no thickness change at all).
Quite frankly, there really isn't that much difference between most sword weights, even considering changes over time and comparing between western and eastern. Most sit around the 2.5lb - 3.5lb range. If you're making a weapon that a human has to use with their hand or hands, regardless of what armour or lack thereof they were meant to go against, you'll come up with pretty similar results all around the world. Heck, even warhammers and such were in the 2-3lb range, it's just that they had all their mass concentrated at the one end.
tl;dr - just get the sword you think is prettiest, because the weights aren't that different all across the board