This one was based off of ShadowLord's idea from the RWBY forums. Basically it's a couple of Swords with some dust capabilities that can separate into whips. This one comes in pairs, so the wielder can choose to dual wield, or have a back-up when disarmed.
Katana: In the sword form it's obviously much more rigid and better for close combat. It also has a chamber in which as special dust round can be inserted at the bottom of the blade. When loaded it can be released up through a tube that runs along the blade as it's swung, allowing the user to make ranged swipes enhanced with properties depending on what kind of dust was loaded.
Whip: The blades can separate into multiple sections connected by a cord. In this image the whip is not fully extended. At full length there's about a foot of cord between each blade section, giving the user much longer range in melee, plus the ability to do actions like wrap around body parts to trip, disarm, or otherwise annoy opponents. Normally the whip can be released by swinging the blades and letting it extend naturally, however if a special cartridge is loaded, then the blades can be shot forward very quickly, which is excellent for surprise attacks among other things. The blades can also be retracted fairly quickly with a small motor to draw a tangled opponent closer, or even possibly to use it like a grappling hook to reach high ground.