@ Megaman 79 and bmmb1
The only weapon (that i know of) that could count as 2 weapons would be the dual blades, but I think those weapons were taken out of MH3 because of how broken they can be unless for Japan with a possible MH3G they could bring'em back. They are awesome weapons for one who truly masters them, but not recommended for beginners.
Waiting...waiting...waiting...waiting patiently for MH3 : p