If you have drawn your firearm on someone that has done something to justify the use or potential use of deadly force then electing to handcuff that person wouldn't be a good idea. Handcuffing a aggressor, suspect, assailant, or whatever you want to call them is an extremely dangerous situation, one that an untrained civilian should never attempt, especially if they were to be by themselves. For the most part if a police officer has drawn a gun on someone they believe to be dangerous, they will wait until backup arrives before they attempt to place the suspect in restraints(unless there is no back up, the back up is some ridiculous length of time away, or the officer is a cowboy or just plain stupid. The best thing you can do is to keep a good distance away from you and the person you have drawn your weapon on.