Divine Stone of Returning Soul

Divine Stone of Returning Soul is one of a kind item in «Sword Art Online». It can be used to revive a recently fallen player. The item can be activated on the player's shortcut menu or by holding the materialized item and shouting «Revive ... Player Name». The effect will only work during the time frame between death of the player to the disappearance of item's effect light, which is approximately 10 seconds. The only way known to obtain it was to fight Nicholas the Renegade in Christmas Event and defeat him.

Kirito is the one who got the item in the hopes of bringing back Sachi but learned about the 10 second rule so he gave it to Klein.