Much like Tanjiro's, the swords used by other members of the Demon Slayer Corps. are also reflections of the traits of their wielders. For instance, while Zenitsu (Hiro Shimono/Aleks Le) is often depicted as a coward, the sleeping warrior within him causes his sword to bear markings that reveal his thunder-breathing prowess. Similarly, Muichiro's (Kengoku Kamanashi/Griffin Burns) blue sword and Mitsuri's (Kana Hanazawa/Kira Buckland) pink sword are indicative of their breathing styles. Still, this raises further questions regarding another of the central characters in "Demon Slayer" — Inosuke (Yoshitsuga Matsuoka/Bryce Papenbrook).
Inosuke's blades are serrated but otherwise standard in their appearance, despite having the ability to kill demons just as effectively as the blades of any Hashira. Though we still don't know how Inosuke got his dual blades, the fact that he lived a barbaric lifestyle in the mountains before audiences are introduced to him does suggest that he may have gotten the blades illegitimately. However, the possibility also exists that he gained his weapons through legitimate means. Inosuke's beast-breathing style is said to have an indigo-grey coloring, meaning he could have been the one to change them to this shade.
In the wake of the Swordsmith Village arc, it's probably fair to say that we know more about the Nichirin swords and how they're made than ever before. However, with the Hashira Training arc right around the corner, it's possible we'll gain even more insight into the blades as well as their wielders.
