I recomend you use the pistol silencer when you want to kill a opponent in the back, or when you hit the opponent with the bow and you use the pistol silencer to finish it. I don't recomend using the pistol silencer in a short or medium-range confrontation, because pistol silencer makes your pistol shoot slower and it decreases slightly your damage, so i recomend you to turn it off and kill the opponent. If you have an agile finger, pistol silencer will be a nice idea, but only for long-range ( but sometimes you can use it in a medium-range ) and for stealths kills. I really recomend you using this DLC, but you'll need to know the right time to use it, pistol silencer is an awesome ''thing'' to take your enemies by surprise!
( Sorry, english is not my native language. )