If Quinn should get a rework. Here is how I would do it.

If there should be any changes to Quinn, they should keep her as this really high mobility champion, so I moved her ult into her passive while still keeping the old passive. Most of the changes are on the ult and passive, the Q only got a small change. But what I tried to do was to make Quinn's Marksman, Assassin style a little better, with now Quinn's Q being able to pull an enemy close to make the enemy easier to hit when she ults. The E just got a change to where it does not slow until you have your ult active, also you get that extra chacing power on her Ult E because you will be able to stick to an enemy and slow them for a little bit. Else, the E is the same as the old one. The ult is completely changed, I tried to make it fair by turning her into melee when active, but also to give her that Assassin style ability.

Passive - Behind Enemy Lines / Harrier: Every 5 seconds Quinn is out of combat, Valor flies down and picks up Quinn. Increasing her Movement Speed (20% to 130% (based on level)). Valor periodically marks a nearby visible unit as Vulnerable, revealing them for 4 seconds. Units hit by Blinding Assault, Vault, and Striking Vault will also be marked as Vulnerable. Quinn's next basic attack against a Vulnerable target deals 15 - 100 (based on level) (+ 16% - 50% (based on level) AD) bonus physical damage.

Q - Blinding Assault: Quinn signals Valor to fly forward in a line, stopping when he collides with a unit, dealing physical damage. If that unit was an enemy champion, the collided unit is pulled back, slowing them by 50% and apply nearsighted for 1.5 seconds. Non-champion targets are disarmed instead for the same duration.

W - Heightened Senses: Is the same as the old W, but the MS and AS passive is removed. When Quinn Ults, she gains vision but also a movement speed boost of 100% if an enemy is revealed from the fog of war.

E - Vault: It will not change, this ability is really good. But she becomes unstoppable and does not apply the slow.

Ult E - Striking Vault: Quinn dashes to the target unit, dealing them physical damage and slowing them by 50% which decays over 1.5 seconds.

R - Azurite Stance: Quinn switches to her dual blades for 10 seconds. Quinn increases her AD by 50 to 80 and AS by 70% to 100%. But her range is decreased to melee range. The E is also changed to Striking Vault.

Let me know what you think. Good change or what would you change if you got the chance? Would you keep her Marksman, Assassin style, or would you change that?

The reason for the duel blade idea:https://vignette.wikia.nocookie.net/leagueoflegends/images/f/fa/Quinn_%26_Valor_Early_Concept_2.png/revision/latest?cb=20161228191806