Isn't Flora's ability inefficient?
There's actually a fencing style based entirely on the drawing of the sword called Iaijutsu. For a reference, the Ukyo Tachibana character from the game, "Samurai Shodown" uses this technique, drawing the sword as a form of attack and re-sheathing the blade all in one move. There is also Iaido, "a modern Japanese martial art associated with the smooth, controlled movements of drawing the sword from its scabbard or saya, striking or cutting an opponent, removing blood from the blade, and then replacing the sword in the scabbard." Though in practice, the Iaido isn't a super fast movement. But again, the emphasis is on the sheathed sword being a starting point, so in order to perform another move, the sword has to be re-sheathed. 

The Iaijutsu article mentions that there is two postures for executing the technique, the standing position or the kneeling position, but both involve the sword being sheathed and using the drawing of the sword as a strike. Obviously, there's no real world instance of someone doing this as fast as Flora, but the technique is that the starting point of the strike is from a sheathed sword.

Other well known users of this technique (though not necessarily the only technique that is used):


Goemon (Lupin III)
Himura Kenshin (Rurouni Kenshin)
Ginkaku Uneri (Katanagatari)
Honoka (The Third)