This is seems strange that a file is forged for the blade and yet the knife is well made, as is the sheath.
It seems that the craftsmen were available but quality steel was not (at least when this knife was made). Unless there was a shortage of steel at that time, perhaps, due to certain factors say, war, trade embargo etc.
This knife is a bit of a puzzle
Edited addition,
I didn't see your last post Tim until I posted the above.....it seems that we are drawing similar conclusions