The protagonist of Final Fantasy VII uses gigantic broadswords as his weapons of choice, the Buster Sword being the most iconic one. However, we think the Fusion Sword is a more original, unique and overall cooler blade design.
The Fusion Sword is actually a set of six different sabers, which come in a variety of shapes and sizes. Not only can Cloud separate the swords and unite them as he pleases, adapting the blade to any situation, he can also use all of them in conjunction for his final signature move, Omnilash.
The concept of an enormous sword composed by several smaller ones is simply awesome. We would love to see different versions of this idea in other games (Nioh and Onimusha, anyone?), as we cannot recall any other title that has a similar weapon.