Piercing claw drops from two particular small monsters (be sure to have your difficulty set to 6+ stars):
Jagras in the Ancient Forest Shamos in the Coral Highlands
Both of these small wyverns-like drop the material regularly, so feel free to farm them at your leisure. They respawn as soon as you leave the zone, so be sure to zone out and back in for peak efficiency. Also, there is no fear of losing out on the material because of damage, so use whatever weapon you have equipped.
Good luck on your hunting, hunters. Want more tips and don’t know where to start? Check out more at our Monster Hunter: World guides. Here are some to start with:
Beginner’s Guide - How To Always Be Ready For The Hunt How To Mount Monsters Easy Vespoid Harvesting Finding The Great Hornfly in MH World Monster Hardbone Farming Locations Elderseal Weapon Guide How To Unlock Kirin Rathian Elemental Weakness Guide How to Beat Rathalos Nergigante the Elder Dragon’s Weakness