As befitting an avowed pacifist, the special moves of Syou Fu Kan's secret sword techniques are all counters. He did not use Formless Rogue Sword: Eight-Way Arrival until Zan Kyou advanced upon him first. Likewise for Formless Rogue Sword: Specter Shattering, which Syou Fu Kan doesn't move and waits for Chou Mei to bring himself into range. Setsu Mu Syou even emphasizes this aspect. He never launched an attack on Syou Fu Kan during their conversation because every scenario he imagined would result in Syou Fu Kan successfully countering his assault.
Setsu Mu Syou dearly wants Lin dead. In the finale, Lin reveals himself as possibly the strongest person in the show, after Syou Fu Kan. Setsu Mu Syou is after Lin not because Lin stole an item from him, but because Lin stole his title and self-assurance in being the strongest swordsman, which Setsu Mu Syou can never get back so long as Lin lives. He isn't trying to kill Lin out of revenge alone, but so that he can retake his title as the strongest warrior in Dong Li.
The movie also shows that Setsu Mu Syou sorely wants Lin Setsu A dead because Lin stole from him the ability to ever be considered an honorable swordsman by rigging a competition in his favor by getting Syu Un Syou to kill most of the other contestants.
Throughout the series, Syou Fu Kan is seen fighting with his fists and feet, an umbrella, a scabbard, and the handle of his sword. Other characters such as the One-Eyed-Impaler and the Frozen Wonder incorporate martial arts, but Syou Fu Kan utilizes tools other than the blade of his sword far more often. There doesn't seem to be a Thou Shalt Not Kill policy in play and he fairly easily kills mooks without a sharp edge. Seems like an extra waste of effort... until you learn that Syou Fu Kan's sword is just a wooden stick painted silver, and, in order to kill with it, he has to undergo the difficult process of channeling chi through it to give it an edge. He has been intentionally handicapping himself in every single fight he's been in in order to make him feel the actual emotional and physical weight of having to kill someone.
According to Syou Fu Kan's impostor, he was never given a name or identity of his own after the Onyx Demons took him in when he was a baby. This may be true of all nameless Onyx Demon members who work under Betsu Ten Gai. It might be possible that Zan Kyou, Ryou Mi, and Chou Mei were never given names until Betsu Ten Gai gave them proper names after they fully master most of his arts.
Lin Setsu A's agenda to steal the Tengyouken for his own gain is very unsettling when it's shown that he was able to convince two of his enemies, Kei Gai (by telling her that Betsu Ten Gai could kill someone like her) and Setsu Mu Syou (by telling him that he can have his head afterwards), to join his team. He had intentions to kill Kei Gai after using her for a trial and he would easily be able to kill Setsu Mu Syou with a powerful weapon. Somewhat averted that Kei Gai ended up being Evil All Along, probably more evil than Betsu Ten Gai himself.