The Morph Weapon is a kind of Swiss Army Weapon. If you want another way to get many weapons for the price of one, see Bifurcated Weapon, a weapon that can be separated into smaller weapons. Some of the below examples overlap clearly with Ninja Pirate Zombie Robot.
Three, five, ten, and more weapons, all in one one neat, easy to carry, easy to use package. They may have various moving parts that need to be flipped around, or they may have some Shapeshifting capabilities, but the results are the same. These are weapons that could transform from one form to another. Well, if you're one of those people, look no further than the Swiss Army Weapon! So what can a character do if they want the versatility of, oh, say.
Even if they could, they sort of have to rummage around their stuff to look for that one weapon that'll give them the edge, which is a bit of a problem in the middle of battle.
Unfortunately, carrying around many weapons is a hassle-not everyone has a Bag of Holding, after all. It gives you more versatility in combat, letting you handle more problems than someone with only one weapon. Having more than one weapon is a good thing.