The sword must pierce the heart of the vampire the wielder intends to trap inside the Phoenix Stone, otherwise the vampire in question will just be injured and scarred for the blade. Because of the powerful magic in the blade, any vampire who is stabbed with it will develop an X-shaped scar that even their enhanced cellular regeneration cannot heal, regardless of where they were stabbed. However, the sword must have the Phoenix Stone attached to its hilt in order to be used for this task, otherwise the sword is just an ordinary blade that cannot kill a vampire if stabbed through the heart. When this occurs, the stone begins to glow from within, and the bubbles under the surface start to move rapidly as the vampire's soul is essentially sucked inside. When the stone is affixed to the end of the sword's hilt, the stone's magic is shared with the blade, allowing it to be used to trap a vampire's soul inside the prison within it when the blade is pierced through the heart of the vampire in question. It has recently been revealed that the stone is paired with an shortsword with an X-shaped blade at the end called The Phoenix Sword.

The stone's primary function is to act as a metaphysical prison for the souls of any Vampire stabbed in the heart with it and keeps them trapped inside. Bonnie mentioned in passing that the Phoenix Stone was a powerful artifact of Native American origin. Prior to this revelation, little was known about the history of the Phoenix Stone, and even fewer written accounts regarding the stone's creation and use as a weapon seemed unavailable, as none of the books Alaric sought out had any concrete information regarding the relic and its purpose. Before it was activated, it seemed pale-grey in color, but when it was activated it turned blood-red with swirling bubbles within it and a hint of a glow. In This Woman's Work, the Phoenix Stone was created by Shamans drawing power from a 'Great Spirit' that was called upon to link Rayna's spirit to it.

3 Throughout The Vampire Diaries Series.

Healing Hand by Nora Phoenix