User blog comment:Nick D Wolfwood/Questions questions questions!! Kurosakigate.../@comment-44061-20100624172823

Theres no bases for the first thing from what we already know. There is only four shinigami forms of combat (Zanjutsu, Hoho, Kido and Hakuda). Karate and stuff are human combat techniques. Also all Zanpakuto work along the same core principles. Renji, Rukia, Byakuya and the many others could say the same thing about their zanpakuto spirits teaching them techniques as well. Isshin states these guys dont want to teach use these moves. Making a broad claim either about the two of their zanpakuto spirits or zanapakuto spirits in general. Seeing as a full compliment of shinigami haven't reached full skill in their respective zanpakutos.

Isshin knew Zangetsu was Ichigo's zanpakuto cause he like most characters around Ichigo have heard it before. Considering he has been aware of Ichigo's actions as a "Shinigami" he is likely aware of its name among all the other things. Zanapakuto names arent secret the only thing someone isn't likely to know is what the spirit looks like. The fact is that shinigami go around all the time saying their zanpakuto name and release commands and technique names and bankai name.

As far as the Ukitake & Shunsui thing. Shunsui already stated that bankai are last resorts. Considering how powerful shunsui's shikai is his bankai probably would have done more harm then good in the situation and why would he use it if he didn't need to at that point he hadn't even used his shikai's powers partially.