I have been shooting for a very long time, in training, competition, and recreation, and I have come to the conclusion that trigger control is the heart of the matter. It may be that I am too particular about good trigger action, but I do think it is the most important single aspect of hitting what you shoot at. It is possible that good trigger action is not important in weapons intended for combat or the hunting of dangerous game, but I do not believe so. Certainly you do not need perfect trigger action to flatten a tiger in full charge at fifteen paces, nor to hammer a goblin across the counter. Still I find that even in coarse shooting I am not just more precise, but distinctly faster when using a good trigger.
Visual observation is, oddly enough, more useful than touch.
You do not have to aim-in. Simply point the piece in a safe direction, place your finger on the trigger, take up the slack, and press gently. If you can see your finger move before the striker is released you do not have a good trigger. Weight is not vital, but it must be considered. In my opinion, a service pistol should break at four lbs or a little under.