A lot depends on the 'fight' in the victim. Some people have 'died' (or at least permanently lost consciousness) at the first strike to something major, even fairly immediately. Others have finished fights, had a drink and made it to hospital after severe injuries to major organs. The will to live in some people borders on the supernatural, and yet, others, seem almost desperate to leave their bodies, or at least fall into shock/unconsciousness at the first sign of trauma. You can get away with a lot here, i mean, assuming it fits your character. If you just need a victim to die quickly thats fine. If you need that victim to paint half the street red with blood and save the day first, that might be fine as well.
If you follow criminal proceedings, one thing you'll see is the occasional killer saying something like, 'Yeah, it wasn't like on TV at all...' People trying to emulate all these quick and neat assassinations, and almost always doomed to messy failure. I've red about guys that spent a LOT of time and effort, trying to snap some poor kids neck, 'like in the movies'. Walk up and twist the head till the neck snaps. Nope. They cranked on that poor kid's head for minutes. They ultimately had to beat him to death with rocks. Others thinking they could just cruise up behind someone and drop them cleanly with a single stab wound. Nope. Big, loud, sticky mess. The stab through the brain stem gets used a lot in movies, but i'd wager that the pro that could pull this off more times than not is exceedingly rare.
I remember, ages ago, watching some TV program about the evolution of killing technology, and specifically, swords. From the blunt and rough bronze gladius type stuff, to the modern and 'utterly perfect' rapier. 'No need for armor when you can just stab a man through the heart with a 3ft icepick, and drop him like a sack', it touted. Again... NOPE. So much 'Holy-wood' myth out there.
Blades will always be messy, and almost never immediate, unless your killer is true Hollywood elite, or incredibly lucky.
My vote would be for a quick, vicious ear to ear slash, or two. You get it all, blood, air, voice, and there's no fixing it. Takes some strength, conviction and command (the real difference between elite killers and amateurs), and its messy, but dammit... it is DONE. Poor girl...