I concurr, it's just adding weight to the tip to increase the cutting impact of the working area, much like the adding of a 'yelman' to the newer model shown in the thread.
I was trying to say that there doesn't seem to be any "added weight" with the traditional blades: I'd posit that the amount of metal behind the edge stays fairly constant (until for the very tip area, obviously).
Consider the bladesmith starting the final forging work with a billet of even width and thickness - probably quite close to the intended proportions at the future base of the blade. Then one starts to widen the blade by gradually forging out the edge: The wider the blade is forged, the thinner it gets; after the widest section, the back of the blade gets/stays thicker because the width is decreasing again. Only after the thickness is finally decreasing towards the very tip (and the width also being reduced towards the point, is there considerably less metal behind the edge...
If one were to (transversally) cut the blade into even slices (say, 10mm), each of them would weight (almost) the same if my observations are correct. It is possible that there is a bit of distal taper (actually quite inevitable if the bladesmith progresses from base towards the tip during forging) - often this seems to get overestimated though, especially when concentrating on the thickness along the back of a blade. The side profile can lead one astray as well. It really is important to see any blade as 3-dimensional object!