Hello Marc,
I agree it is very odd how they appear to have been made. I almost never encountered single piece blades. Joining the two plates of blade seems peculiar but that is how they were apparently produced...although I never actually took a blade apart to confirm it. The other oddity about blades is the very short tang... something like half an inch only....and not rivetted ...simply glued. Khanjar makers in Oman imported blades and the performance of some buyers was quite amazing and despite the expense of a good hilt...Rhino or Giraffe...or Ivory much attention was given to the blade where
it was said ...that the finest steel was obtained from metiorites!!
Having said that...
The following is a brilliant treatise on Khanjar making at
https://core.ac.uk/download/pdf/195632974.pdf where the whole story unfolds including the forging of the single blade...
Peter Hudson.