Arcane Sigil

Arcane Sigil is an Armor prefix only available on Docents. It reduces the wearer's arcane spell failure chance by 5% or 10%.

Since Update 17 (or earlier?), Arcane Sigil works similar to Arcane Casting Dexterity enchantment and does not stack with it. Also, different tiers of Arcane Sigil no longer stack. Forum discussion.

Lesser Arcane Sigil
Effect: Reduces the wearer's arcane spell failure chance by 5%.

Found on:
 * Dragontouched Armor
 * Morleth's Docent

Arcane Sigil
Effect: Reduces the wearer's arcane spell failure chance by 10%.

Found on:
 * Dragontouched Armor