A talisman was an item given by Duke Horacio in the old version of the Rune Mysteries quest. It looked like an air talisman but cannot be used as a runecrafting talisman. It was used only in the quest.
Before an update that changed the item from an air talisman into a talisman, players could do the drop trick to receive multiple air talismans from Duke Horacio during this part of the quest. This could only be done if the player had started the quest Rune Mysteries and had not finished the part where the player showed the air talisman to Wizard Sedridor. This led to Jagex changing the air talisman in the quest to a talisman.