And while you’re at it, since you kept using your “vein” argument, you may want to explain your apparent premise that it would be difficult for a trained assassin to find an intravenous point of entry.
So you think that hitting a vein dead center through clothing at long range, which it has to be since the pistol has a scope on it, would not be hard? You think that the impact of a dart traveling fast enough to penetrate skin and vein would not be noticed by the person it hit? You think that the frozen dart would not be melted by whatever propellant was used to shoot it? If you believe that then nothing I can ever do will convince you otherwise.