The Witcher (PC) Edit

Whetstones increase damage inflicted by 10% and may be used on either silver or steel blades.

Sources Edit

The Witcher 2: Assassins of Kings Edit

Geralt starts the game with 10 whetstones in his inventory. As of the latest version, there is the option to enable/disable the provision of whetstones in inventory from the start of the game.

Whetstones are not available for purchase, no known monster has whetstones as loot nor are there any loot containers containing whetstones in the game.