Draco's clone performed the first Sword Skill Draco possessed, which was Inclined Slash. This was a Sword Skill that was pretty simple, and had a normal motion as well as a normal effect.
However, it was enough for this purpose. Draco had never used Counter Kill in this life so far, because honestly, he was not sure he could.
It was like the strange transformation from one of those evergreen Dragon Ball anime series, where Goku became grayish and could avoid almost all attacks due to some special instinct.
In the beginning, he could not willingly activate that mode, but after he had successfully grasped it the first time, it was - relatively - easier to do so the second time.
The same applied to Draco. Thanks to the way his memories of the previous timeline worked, he could perfectly remember the feeling of using the technique and entering that mode, as well as what that mode felt like.
