The order to 'brown' = 'blue' these bayonets came in the 1930's IIRC (?1933?, as that sticks in my mind). Certainly an odd style adopted here, though!
The lack of a 1920 stamp is not in itself a big deal as this could have been ground off, but the lack of a Reichswehr unit stamp is more of a puzzle.
That aside, the great majority of dated bayonets of this type are, I think, 1915 or 1917 - for some reason 1916 examples are uncommon, and 1918 ones very rare - if they exist at all!
Julian
The lack of a 1920 stamp is not in itself a big deal as this could have been ground off, but the lack of a Reichswehr unit stamp is more of a puzzle.
That aside, the great majority of dated bayonets of this type are, I think, 1915 or 1917 - for some reason 1916 examples are uncommon, and 1918 ones very rare - if they exist at all!
Julian