The allure of imagination is so great that sometimes people have a hard time ‘letting go’, even when the experts have pronounced and have the evidence to back it up. The most basic survey of the literature, or even an online search, would have raised serious doubts as to the warlike nature of this axehead, if not its ‘Viking’ pedigree or its actual identity as a post-medieval tool.
The uncharitable amongst you might suggest that anyone who would put that on display as a Viking axe must themselves be a ‘post-medieval tool’.