Holy Lance

The Holy Lance, also known as the Holy Spear, the Spear of Destiny or the Lance of Longinus, is the lance that pierced the side of Jesus as he hung on the cross, according to the Gospel of John. Several churches across the world claim to possess this lance.

The lance (Greek: λόγχη, lonkhē) is mentioned in the Gospel of John (19:31–37), but not the Synoptic Gospels. The gospel states that the Romans planned to break Jesus' legs, a practice known as crurifragium, which was a method of hastening death during a crucifixion. Just before they did so, they realized that Jesus was already dead and that there was no reason to break his legs. To make sure that he was dead, a Roman soldier (named in extra-Biblical tradition as Longinus) stabbed him in the side.

One of the soldiers pierced his side with a lance (λόγχη), and immediately there came out blood and water.

The phenomenon of blood and water was considered a miracle by Origen. Catholics, while accepting the biological reality of blood and water as emanating from the pierced heart and body cavity of Christ, also acknowledge the allegorical interpretation: it represents one of the main key teachings/mysteries of the Church, and one of the main themes of the Gospel of Matthew, which is the homoousian interpretation adopted by the First Council of Nicaea, that "Jesus Christ was both true God and true man." The blood symbolizes his humanity, the water his divinity. A ceremonial remembrance of this is done when a Catholic priest says Mass: The priest pours a small amount of water into the wine before the consecration, an act which acknowledges Christ's humanity and divinity and recalls the issuance of blood and water from Christ's side on the cross. Saint Faustina Kowalska, a Polish nun whose advocacy and writings led to the establishment of the Divine Mercy devotion, also acknowledged the miraculous nature of the blood and water, explaining that the blood is a symbol of the divine mercy of Christ, while the water is a symbol of His divine compassion and of baptismal waters.

...
Wikipedia