One thing about FPS gameplay... I don't want ironsights in, but if they are going to be there, I'd want perception to affect it a great deal. More specifically the range of vision. In effect, you can shoot from the hip, but at a penalized accuracy where it is quite literally "praying and spraying"; or you can pull the sights on the screen where you have more precise knowledge over where the bullets land (still affected by the governing skill and stat through sway and recoil distortions) but perception affects the range of your sight by providing http://fatigueness.com/wp-content/uploads/BLURRY-VISION-FATIGUE.jpg and http://www.happyfeetformula.com/blog/wp-content/uploads/2013/10/106397123.jpg on enemies and objects at certain distances - also for VATS distances (how ever that thing is made... but that's another story). This to ensure that a halfblind sharpshooter isn't a thing and to keep the stats effective.