Why is Quinn labeled "Marksman/Fighter"?
I understand the Marksman bit, but Fighter?
From the League of Legends Wikia:
Fighter: A hybrid champion ... that combines the survivability of a tank and the damage of a DPS or a caster. They were formerly called Bruisers.
But does Quinn really have the survivability to justify her Fighter label? Sure, she's good at 1v1s in the right hands, but this is in part due to her burst and blind, not her defenses. Methinks Assassin would be a more appropriate label for her secondary:
Assassin: A champion type whose forte is rapidly ambushing and slaying enemy champions. They have abilities that may include stealthing themselves or having a strong dash skill.
Quinn's ult not only puts the player melee, but grants him/her a massive AS and MS boost, as well as a targeted dash to help Valor stick to his prey. Any squishy target that's out of position and isn't massively ahead of Quinn can very well find themselves 100-0ed in a swift flurry of feathers and claws.
Not that it's a big deal, but I do think Assassin would be more fitting, as that is what her ultimate is good for.
needs you :(

or
, aren't really that tanky, and
in melee form, and has more burst than the average marksman (especially against low-health targets), but doesn't quite fit the assassin model, particularly since her melee form lacks an escape of its own. It's likely Valor should be changed to be more of an assassin, but right now Quinn's more of a marksman-fighter than a marksman-assassin.
Here's how Quinn is a fighter. Only Vlad and similar champs can survive that.