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Sleeves are a part of the Cloth Armor set, worn by mystics, priests, and sorcerers. The set also includes a robe and a pair of shoes. The Cloth Armor set provides very low defense and balance modifiers, requiring the wearer to rely much more on dodging, avoiding damage, and self-healing.
Sleeves can be obtained from various methods, including NPC shops, other players via direct trade or via the Brokerage, enemy drops, reward from quests, or crafting through the skill Tailoring.