Oh yes, I'm sure she is. I don't have too much experience with the Witcher series, but from what I do, Geralt is a bit of an abnormality in terms of strength, speed, and skill, and even he considers Ciri a prodigy, which is indicative that she's highly skilled. That being said, this Retsu clashes with (and albeit lost to) Miyamoto Musashi, the most skilled weapon user in the verse. He's so skilled in swordsmanship, his skill is more or less a bridge between the likes of Yujiro Hanma and the rest of the verse, Yujiro eclipsing even most of the high tiers in the verse in skill, only a few being comparable but significantly less skilled than him. Musashi is also such a skilled swordsman that he can accurately imitate a sword with his bare hands so perfectly, slashing people has results varying from people feeling the cold steel slice through them to even 1 man claiming he felt all 3 trillion of his cells dying. Retsu was such a match for him, he compared Retsu to the entire Battle of Sekigahara, one of the bloodiest and most brutal battles of the feudal Japan Civil War era, a battle that Musashi engaged with both sides, fighting both armies by himself and winning
