In The Witcher computer game Edit

Moon rune
Magical rune that can be branded into silver blades
Description
Type	Weapon upgrade
Effects	Increases opponent's sensitivity to silver + 10%
Price to buy	800
Price to sell	160

Locations Edit

• In Chapter III, found on the corpse between the 2nd and 3rd archways in the kikimore queen's lair.
• In Chapter IV:
  • found in the chest on Black Tern Island (near the circle of elements).
  • received from The Rock, one of three possible rewards.
• In Chapter V
  • sold by the fence.
  • found in a chest in the courtyard of the old manor.
  • found in Agnes of Glanville's trunk.

In The Witcher 2: Assassins of Kings Edit

Moon rune
Rune. Sword upgrade
Description
Category	Rare
Type	Crafting component / Sword upgrade
Effects	bonus on Signs +4
Source	Starting equipment / Craftable / Purchase / Loot
Price to buy	211 / 264 / 301 / 376
Price to sell	16
Weight	0.2

Geralt starts the game with one moon rune. Later, they can be purchased from a number of merchants, including the mysterious merchant, Haggard or Thorak in Vergen, or Falas, the Incredible Lockhart or Polycarp of Rinde during Chapter III.

To use a rune, Geralt simply drags it over to one of the rune slots on a suitable sword in the inventory panel.

Moon runes can also be used to craft blue, red or yellow meteorite ore, though given that the price of a rune is significantly higher than that of a piece of ore, it seems a poor use of the rune.