Personally I consider Sasaki better than Musashi as a swordsman. She basically cheats using her Mystic Eyes and Magic swords. To be the rival of someone who gives causality the middle finger by looking at it while just being a DAM good swordsman. Bravo. Even better he broke REALITY through his sheer skill. Can Musashi do that? On skill alone? No. Bow before our Regend.
Essentially Musashi is the new Aoko, so you have Kinoko giving her life up praising Musashi. ... Okay, let's put the Aoko joke aside. Then, Battle Continuation EX, LOL. ...... Okay, Battle Continuation is nothing to worry in a duel. Then, Sasaki calling himself a heretic swordsman makes him vulnerable to Musashi's other NP, a NP specifically targeted at heretic, even evil swordsmen. What makes this funny is that Musashi only used this NP once in her life, and nobody really knows how it works. So, Sasaki died by being heretic. LOL. ......... Okay, all jokes aside. (Material from FGO Material 5) While Sasaki breaks reality, Musashi breaks CAUSATION. Her NP (while written as Anti-personnel) is actually anti-causation, being able to break karma, curses and bleak fates. Her Mystic Eyes (being able to limit all the parallel future to one) are basically the polar opposite of Sasaki's Tsubame gaeshi (and are active only when she decides to cut off something, so she might not be able to use her Eyes on trying to take Sasaki's NP). It is also specifically stated in the description of Nothingness A skill that even if one strikes with the power of Multi-Dimensional Refraction Phenomenon, one cannot reach Nothingness, and that Nothingness is the highest any swordsman can ever reach (equivalent to Suigetsu, on a side note). So yeah, Musashi received the blessings of the entire Type-Moon (especially Miss Nasu) to be the ultimate swordswoman. So, basically, Okita Alter (joke character privilege) >>>>>>>>>>> Musashi after Shimosa Province =? Yagyuu > Sasaki > Musashi before Shimosa Province (technically Musashi was alive during Shimosa Parallel Singularity), Okita (I can almost recall where I saw the article calling Okita's NP "similar, but different to" Sasaki's NP) >? Izou (cannot replicate NP-level skills) >>>>>>>>>>> Jalter Berserker (She's not even a swordswoman). Edit: I'm just really, really tired of the Regend meme, that's all. Apologies in advance.