Not to mention the way you describe it has nothing to do with how it seems to be used, which is like a giant double ended halberd.
I bet from the three words shotgun/surfboard/axe I can make a better weapon that seems to actually be used the way it sounds.
Well, it doesn't actually use a simple combat style. It spins, it morphs, it can eat Dust and let him tear through Ursas by simply firing his shotguns rapidly to propel himself through the Grimm, and he can detach the axes from the hoverboard whenever he wants.
And the weapon doesn't just stay like the way it appears in the image! xD It's supposed to be a versatile weapon that can take many forms, including a shield, a double-barred Dust cannon, and a great longsword that can coat itself with Dust (the one that appears in the image is simply used when he feels too lazy to transition from one form to another). That's also where I decided not to go with using the weapon; it's too versatile and useful when it comes to utility and power.