What I know to be acceptable is that one can eat it with fingers, or chopsticks, always use the other end of chopsticks for communal plates, and one can eat it with two bites, dip the fish not the rice in soy/sauce.
So onto my query. I am considering some high end places on an upcoming Manhattan trip. Would it be acceptable to ask the sushi chef to cut in half pieces of sushi on rice? I have a 4 tooth bridge that is not nearly as sharp as the chef's knives.
Would this be an insulting request?