Nano Arms transforms the Keyblade into a nano-bladed broadsword with twin blades sticking out from the sides. It can then transform further into a variety of black-shaded nano weapons, which resemble the Clock Drill, Blizzard Claws, Hyper Hammer, Storm Flag, and Twin Yo-Yos Formchanges.
In Kingdom Hearts III, Nano Arms is the Formchange of the Nano Gear Keyblade, associated with Blitz Form. It has a base duration of 30 seconds and a maximum combo length of 6. Its basic attacks are identical to Sora's basic attacks, but its Nano Transform ability allows it to mimic attacks from various other Formchanges: Blizzard Claws' Winding Strike, Hyper Hammer's Ground Wallop and Flying Clobber, Clock Drill's Dire Drill, Twin Yo-Yos' Backspin and Anchor Shot, and Storm Flag's ground-to-air attack. Its sole combo finisher has Sora form a fist out of nano and fire it forwards.
The Finish command has Sora leap into a portal before generating several other portals around himself and firing streams of nano out of them.
Learning Nano Arms
Kingdom Hearts III