Hi, sorry I missed participating in the hunt!
For future searches, remember there are lots of different ways to spell the name for a knife as well as different names for the same artifact. Search engines are seldom smart enough to look for all the variations.
Here are all the different ways I have seen to spell bichaq:
bıçak, bichaq, bishaq, bichac, pichoq, pichok, pchak, pechak, P’chak
I try to document the ones I find. Here is list on my website with some that might be helpful. Good luck!
https://atkinson-swords.com/nomencla...-equivale.html