Originally Posted by JandK
Yeah, the sharpshooter feat has to be coming from some mod.

It is from this author:

Feats

More feats

For those that mod, they are great to try out. The sharpshooter confused the AI, and did not immediately trigger combat. They do hunt you though, so if you want to stay hidden, it is best used by leaving your party back, and picking your position well; staying mobile. Not my favorite play-style so far, but very effective.