Thanks for the comments Philip. For sure the szabla has been dismantled at some point. The rivet would have been replaced then, hence why it looks odd. Perhaps this happened a while back, and the leather could have been replaced at the same time (hence lack of age).
I don't own very many European swords with age and leather, one Danish sword I have from 1845 is in much better condition wrt leather (and I am certain genuine). So based on my admittedly extremely small sample size I say the leather here was not put on in the last few years, but I would be astonished if it was as old as the sword should be. If it were genuine I guess this should be 18C?
Btw I did not pay Bohmans karabela prices for these, so nobody robbed me
