I don't know if it's the exact same problem as BK11. But the sheath is made of FRN, and edge rubs on sheath the way it's made. The glass fiber in FRN would dull the sheath instantly. I sold my BK11 as a result.

It's not specific to Kabar, rather any FRN sheath, include many spydercos like aqua salt and rock salt. I fixed my rock salt sheath with a plastic insert.