Not so simple. Why would his wife claim that he can no longer talk, that he can't talk, instead of freaking out that his head is cutoff. That must carry meaning. I also wonder about the trigun title. The only thing I could ever come up with is Wolfwood's cross. At least as something that makes sense. Otherwise, Milly, Meryl and Vash could be the triguns..... although it would need to be plural. It would also exclude wolfwood. I watched that Anime first, and it's too bad, because the really endear wolfwood as a character. I could not imagine having a second "wolfwood" clone befriend vash, albeit with a personality disorder. It ruined the manga for me.