I'm a fan of the Vikings series so I designed this Viking axe head based on axes used in the series as well as research on the web.
I believe the size and shape of the axe is true to history.
I have included some images of actual axe heads.
Because of the size of the axe I had to split to print on my UP printer. That's the first two stl files. I have included the complete axe head as well for those with a larger print bed.