I look at that double snapped one and I wonder if they were trying to make 2 out of 1.
Another try on the one piece.
Then was the shape and the possible application it was intended for as it is now.
My 1st impression was the flat side sat against the shaft, and the notched sides were for the sinew to be securing it to the shaft.
The rounded side was for the intended use.
(Probably too much coffee)