The material below is Open Game Content from a 3PP Source
Sword of Subtlety
Aura moderate illusion; CL 7th
Slot none; Price 22,310 gp; Weight 2 lbs.
A +1 short sword with a thin, dull gray blade, this weapon provides a +4 bonus on its wielder's attack and damage rolls when he is making a sneak attack with it.
Requirements Craft Magic Arms and Armor, blur; Cost 11,310 gp