The dazzling reflection of the blades flashed around everyone like lightning, catching them off guard. Although the speed of the shadows did slow down due to the minor effects of the Dreamy Mageweath, their attacking speed was not affected. It was just like the fact that while running was faster than walking, it had nothing to do with landing strikes.
What gave everyone a headache apart from the speed that seemed to be as fast as lightning was the unpredictable angle of attacks. Even if the direction of the enemy's general movement was known, one might not be able to know which body part the enemy would be attacking. After all, the human body was still too fragile, and almost every part of it was a weak point. The enemy obviously did not have a penchant for slitting throats; as long as it was a fatal spot, anywhere could be their target for attack.