I've been watching Claymore. I haven't read the manga yet.
Number 8, Flora:
She's the fastest there is at unsheathing, slashing, and sheathing back her claymore.
As you can see, she unsheathes, slashes, and sheathes back so fast that the image of her hand seems to be static, whereas a bunch of slashes appear around the target.
But wait.
What is the point of sheathing her claymore back while attacking someone? Isn't that a waste of time? Wouldn't it be more useful to unsheathe and then slash countless times rather than sheathing back her claymore during a fight?
Proof that she's indeed sheathing after X amount of slashes:
This scene below lasts for several seconds. This means that she must continuously sheathe her claymore, otherwise this image effect wouldn't be possible: