Where does this sheath come from?

[A. G. Maisey]

I'm more inclined to think it is a repair, maybe the front of the wrongko was a bit marked/scuffed/indented and somebody outside the society or culture took to it with a sharp knife & some cabinet paper.

If we look very carefully at the top left of the pendok we can see that there is not a flowing line along the length of the janggut section, it sort of runs a bit flat approaching the pendok, then it begins to curve. This shaping is not the work of a bonafide m'ranggi or tukang wrongko.

I am inclined to believe that somebody with very limited understanding decided that the wrongko needed a facelift, so he gave it one that pleased himself.