so here's the thing. "growl" and "hiss" as dialogue tags are fine. they convey a mood. and you can, by the way, absolutely hiss something without sibilants. that said you cannot growl or hiss more than around ten words, especially hiss. physically, that is. both describe constrained speech, through the teeth or at the back of the throat, in a single breath. try it out loud: "stop it" is fine. "take your hands off me" is fine. "I won't be going to the castle, or anywhere else, with you bastards" is not. you can deliver it as a threat, for sure, but not in a hiss. you have so many other options. the language is there, begging to be used in new ways.