Cost — Weight 1 lb.
Damage 1d4 (small), 1d6 (medium) Critical x2 Type bludgeoning
Category ranged Proficiency exotic
Weapon Group thrown
Special disarm, trip
Technically not a unique kind of weapon, a stitched sling is a sling, staff sling, or double sling whose cup is sewn closed around the ammunition, creating a weak sort of light flail.
The ammunition sewn into the sling is irrelevant to the type and amount of damage it causes. A stitched sling cannot be used to fire ammunition unless the thread or cord holding the cup closed is cut open (a full-round action that provokes attacks of opportunity).
Pathfinder Player Companion: Halflings of Golarion. Copyright 2010, Paizo Publishing, LLC; Authors: Hal MacLean and Amber E. Scott.