Pretty much was that guy. Think about how he moves and jumps around.... Think long and hard about it.
But pops knuckles here we go.
I would imagine a younger girl, Young adult, mid 20s. In a robe, since were talking about KH lets say like the Nobodies, their black robes, hooded, concealing majority of the face.
She would weild one Keyblade in her LEFT hand, backwards, mostly as a defense tool, over offense. Right hand she uses her abilities.
(im not getting into numbers, just spitting out ideas)
Passive: When using an Auto attack, she will gain a burst of movespeed that decays rapidly, does not stack, has a cooldown. When hitting an enemy with a ability, she will gain a small shield over her health that decays quickly, does not stack, and has a cooldown.
Q: Uppercut
She lunges forward, not even half of what fiora can do, and uses her backwards keyblade, to uppercut anyone infront, whoever is hit first (goes through minions to hit champions), is knocked back.
W: Kinect Push.
Uses her right hand, to push enemies direclty infront of her, in a cone, away, dealing small damage (think syndra).
E: Vault.
Pressing E, will give you a skillshot to jump backwards in the other direction, giving a short burst of movespeed.
R: Release.
She conjures a mystic form of a second keyblade, with dark energy, this changes her abilities. This only lasts so long, only able to do Q, W, E two times each max, with once on R, and if she does R first, only once on each on the other abilities- maybe.
R-Q: X Cut.
Cuts in a single X cross infront of herself, anyone in front is dealt damage, AD and AP, and heals her for a portion. (very small).
R-W: Self Shield.
Does a powerup, like Yis Meditate, the longer she is able to, she powers up a shield, the longer she goes without getting hit, the stronger the shield, if she is hit, then it is significantly slowed, most CC would stop it.
R-E: Cyclone attack.
Spins like a bullet through a location, dealing damage THROUGH enemies and walls, upon landing, short burst of speed.
R-R: Dark Release.
Sends out a shockwave doing AoE damage in one quick burst, but doing so well lower resistances, and lower speed for a short time and cause other abilities to go on cooldown.
This pretty much makes her more of a mobile disruption juggernaut.
She can use her R to go for damage, but then leaves herself open for less CC, or stay in her base form, to stay around and peel, making her universal.