The weapon I would love to wield would have to be Inuyasha's Tessaiga.
Tessaiga, also known as the Sword of Destruction, has the ability to absorb demonic energy to further enhance itself into the ultimate weapon. This gives its wielder the ability to use various forms of the Tessaiga to make attacks much stronger. It is known that the Tessaiga has a mind of its own, as seen in the anime, and would let the wielder know the proper time to use it. Plus whether in use or not the sword can manifest a barrier to protect oneself.
Although at first glance it may seem like an old battered katana, the Tessaiga is truly the ultimate weapon being capable of killing 100 demons with a single strike.
For theses reasons it would be a dream and honor to be able to wield the Tessaiga.