Why a hole in a Viking Age battle ax

In some axes of the Vikings and some other peoples, including the Slavs. In battle axes, and in axes for household use, there is a hole, the purpose of which is unknown. There are several theories about their purpose, which in my opinion are untenable. Having been dealing with this issue for a long time, I offer my opinion, which may still be wrong. The hole is part of the tool to facilitate sharpening the ax blade. This video is my first attempt at testing the concept. Of course, the Vikings did not use a steel stud with nuts, but it can easily be replaced with a wooden or bone stick. Using the last 2000 grit abrasive and a 33. 3 degree sharpening angle resulted in a fairly good sharpness, which speaks in favor of my theory. I should also note the speed of sharpening, and the retention of the sharpening angle along the entire length of the cutting edge. Another method of sharpening is probably possible using a hole and an object inserted into it. I would be grateful if you could write your interpret