Considering the NS universe in it's second iteration has developed 3D printing technology and parts of the community is displeased with the axed replacing the knife I had an idea.
I say wouldn't it be possible to have a technologically advanced hilt with an incorperated 3D printer beam which prints the blade or Axe directly in the hilt. So upon hitting the alt fire button the hilt pops out and discards the existing blade/axe and prints it's counterpart. Would definently look pretty cool and animations would change dependent on what's in the hilt at the moment.
Just a thought. And this could possible mean you're not limited to only knife blade or axe, the hilt could house all manor of melee patterns to print. But that's a subject for another time. Primarily it could be Knife/Axe.