Helena's Nail

History
Helena's Nail actually refers to any of traditionally 4 different nails, though from the same source. They are the nails used in the crucifixion of Jesus Christ upon the "True Cross". The nails are objects of veneration among some Christians, particularly among Catholics. They are among the Arma Christi, otherwise known as the "Weapons of Christ", which are commonly associated with Jesus's Passion. Legend states that the nails and other remnants of the True Cross were discovered in Jerusalem around 313-327 AD by Saint Helena, mother of Constantine the Great. She left all but a few fragments of the Cross in the Basilica of the Holy Sepulchre in Jerusalem, but returned with the nails to Constantinople. One of the nails is said to have come to rest in the Iron Crown of Lombardy. It is also said that Helena placed 1 of the nails in Constantine's helmet (which is said to have become part of the Iron Crown of Lombardy), 1 in the bridle of Constantine's horse, and 1-2 into the Adriatic Sea to calm a storm (or 1 into the head of a statue). This may not be true, however, as there are many conflicting stories.

Hellsing
In Hellsing, one of the nails somehow finds its way into the hands of the Vatican's Section 3 "Mattai" (Matthew). This is the Vatican's top secret holy relic administration bureau. The relic is given to Paladin Alexander Anderson for use in the battle that takes place in London, but specifically for what he sees as his "final battle" with Alucard in which he is determined to destroy Alucard once and for all, and at any cost.

After challenging Alucard and confronting a massive wave of familiars, Anderson revealed the Nail he had received. Despite Alucard's desperate pleas not to use it, Anderson drove the nail into his heart, allowing him to regenerate from the massive damage he had sustained in the battle prior. His flesh grew back as a mass of thorny vines, barely recognizable as a human. Sadly admitting Anderson had become a monster, albeit a monster of God's will, by using the power of the Nail, Alucard vowed to kill Anderson for what he had turned into.

The Nail's power boosted Anderson's regenerative powers and allowed him to "charge" his bayonets with holy fire capable of grievously harming undead and all "unholy" creatures; these flames were easily extended to all of Alucard's familiars all at once, fatally igniting them. Familiars killed in this manner included Tubalcain Alhambra and Rip Van Winkle. Anderson was also able to near-fatally wound Alucard with one of his blessed bayonets, nearly cutting him in half with a single blow.

However, Alucard's fledging, Seras Victoria, managed to stop him from driving the bayonet deeper and was burned herself by the blade's fire until Alucard, with a supreme effort, managed to shatter the bayonet, charge Anderson head on and forcibly rip his heart and the nail along with it. Unable to live without the power of the Nail holding him together, Anderson crumbled apart and died before his eyes.

Users

 * Alexander Anderson

Trivia

 * A few of the other Arma Christi are seen in Hellsing. These are the lances of the Vatican's Papal Knights (a reference to the Holy Lance used to pierce the side of Jesus Christ on the cross) and the 30 pieces of silver mentioned by the members of Iscariot (30 pieces of silver is said to have been the price for which Judas Iscariot betrayed Jesus Christ, according to Matthew 26:15.).
 * The thorns growing out of Anderson's body may be a reference to the Crown of Thornes, which was placed on Christ's head before crucifixion.