My first thought was Buck 110, as far as one hand opening, add a thumb stud. Anybody who carries a 110 for any amount of time will figure out how to open it one handed anyway.
I'd grab the blade between my thumb and forefinger and flick down. The weight of the handle would pull it open and lock it into place. Mine was well broken in though; I don't know if it would work with a new knife with a stiff spring...
As far as the quick draw sheaths, they are a felony in some places.
Never heard of that (wouldn't put it past someplace like NYC), but it goes without saying: know your local laws.