Lets see: As far as I know; the "best" flee gear would have to be:
Ninetails card, Slotted in a +9 and up Garment. +20 Flee, +2 AGI
This is more prefered over Whisper - due to the fact you don't take 50% more damage from the Ghost property.
Stormy Knight card x2 : +40 flee
You have the possibility of wearing two - one in a top headgear, and one in a mid headgear (For example: SK helm, and SK Evil wing ears.) So that's +40 Flee.
Mysteltainn: +20 flee.
So that's your 80+ Flee.
The main page says:
Stormy Knight x2, Whisper and Mysteltainn Card
Meaning Two stormy knight cards, one whipser card, and one Mystelainn card.
You can also use the Grimtooth Dagger, which I believe gives +10 flee. I'm not 100% sure if it does on this server though.
If you're a Swordsman, You have the possibility of using Masamune, which gives +30 flee.
That's all I know about Flee gears. You also have skills that increase your flee, like improve concentration, and improve dodge.