items can have sockets which hold special stones called Runes. Runes come with a variety of functions but are typically separated into two different categories: armor runes and weapon runes. Runes typically have “tiers” and like Runes can be upgraded by talented smiths. Removing Runes from an item destroys them. Conversely, you can choose to destroy the item (turning it into raw materials) and keep the Runes in tact.
Armor has to be at least masterwork quality to have sockets.
Armor: Leg and Arm pieces can have 2 sockets, Torso pieces can have 4 slots for a maximum of 8 slots.
Weapons: Light weapons can have 1 socket, One Handed Weapons can have 2 sockets, and 2-handed weapons can have up to 3 sockets.
Shields: Shields are special in that they can be fitted with Armor or Weapon runes (depending on what type of socket the armor was crafted with). Bucklers can have 1 socket, Light and Heavy Shields can have 2 sockets, and Tower Shields can have 3 sockets.
Sockets on armor add 150gp per socket to the market value of the armor. Sockets on weapons add 300gp per socket to the market value of the armor.
Runes often have different Tiers, with each higher tier doubling the bonus the Rune provides (additively speaking). So a third Tier rune (often prefixed with “Greater”) of a Rune that confers DR 2/- would instead confer DR 6/-.
While one type of Rune does not stack with itself in the case of multiple Runes socketed, the benefit conferred by the Rune does stack with whatever bonuses the character is currently receiving. For example, two Lesser runes that grant DR 2/- would still only confer DR 2/- but that DR would stack with any existing DR the character has.
Armor Runes can only be socketed in Armor although what piece of type of Armor they’re socketed into doesn’t matter. See the Armor Runes page for additional information.
Weapon runes can only be socketed in weapons, although they typically function in all types of weapons. Some weapon runes exist that only serve a specific type of weapon but these specialized runes are rare. See the Weapon Runes page for additional information.