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If Honedge evolves at all (which I hope it does), these are pretty much what could happen.
One Sword > Sword and Shield > Suit of armor, holding the sword and shield.
One Sword > Multiple Swords > A LOT OF SWORDS
One Sword > A really big sword
One Sword > Some other weapon, like a spear or an axe.
Like some other anon said, if Yamask can evolve into a full-blown coffin, a sword could plausibly evolve into a suit of armor.