That’s a great photo, that axe is similar to a type of axe that the Templar Knights are thought to have occasionally used during the crusades although personally Ive yet to see any real evidence of that. Its definitely a specialist weapon and given that Templar Knights were incredibly skilled horsemen they would have needed an axe with a long shaft to enable them to use it from horseback. To be honest, most of the axes used by the Templars were single bladed simply because a rear spike or (Ravensbill) added to much weight which obviously resulted in a weapon that was heavy and unwieldy. When the Templar Knights attacked they were trained to ride knee to knee this was known as the ‘Conrois’, they were very good at keeping formation and shocking their enemy with speed and accuracy. A knight on horseback in close formation and swinging an unwieldy axe wasn’t really practical, foot soldiers would have been the guys that used double edged axes, Templar Knights using double edged axes is a bit of a myth methinks.
I have seen a number of axes similar to that of the one in the photo but they are mostly used for ceremonial or religious purposes, like I said earlier, its a great photo but to use an American saying, ‘its all a bit Farb.’
Apologies for my lengthy post but I have a slight fascination with the Templar Knights.