Helena's Nail

Helena's Nail (エレナの聖釘, Erena no Seitei) is a dangerous Iscariot artifact used in the Hellsing series.

History
The name "Helena's Nail" actually refers to any of several nails, all 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' 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 Sepulcher 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. Another legend claims that Helena placed one of the nails in Constantine's helmet (which is said to have become part of the Iron Crown of Lombardy), another in the bridle of Constantine's horse, and one or two into the Adriatic Sea to calm a storm (alternately, one of the nails was placed into the head of a statue to achieve the same effect).

The veracity of these stories is nebulous, however, as there are many conflicting stories - even the exact number of nails used in Christ's crucifixion is debated.

In Hellsing
In Hellsing, one of the nails somehow finds its way into the hands of the Vatican's Section 3 "Matthew", the Vatican's top secret holy relic administration bureau. The relic is given to Alexander Anderson for use in the battle of London, but specifically for what the paladin saw as his "final battle" with Alucard, in which he is determined to destroy Alucard at his most vulnerable; after releasing his full power, leaving him with no excess souls to protect him from a fatal blow.

After challenging Alucard and fighting through a massive wave of familiars with the help of the remnants of Iscariot, Anderson revealed the Nail in his possession. 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 one serving God's will- by using the power of the Nail, Alucard vowed to kill Anderson for what he had turned into.

Unfortunately for Alucard, the Nail's power enhanced Anderson's fighting ability far beyond his previous state; the mutated priest regenerated any damage Alucard managed to deal while delivering devastating counterattacks of his own. Anderson eventually pierced Alucard's head from above with one of his blessed bayonets, nearly cutting him in half with a single blow. Before Alucard could regenerate, Anderson channeled the power of Helena's Nail through his weapon, causing the vampire to burst into flames. As the divine fire spread to Alucard's army of familiars (including Tubalcain Alhambra and Rip Van Winkle), the reformed Dracula began flashing back to his earlier defeats, implying that he was in actual danger of death from Anderson's Nail-enhanced assault.

However, Seras Victoria managed to stop Anderson from finishing Alucard off. Although the fledgling was seized by vines and burned by the holy fire, her cries enabled Alucard to regain his senses. With a supreme effort, Alucard managed to free himself from the bayonet and vines holding him. Charging Anderson head-on, the powerful vampire forcibly ripped the corrupted priest's heart out of his chest, taking the Nail with it. The vines immediately disappeared from Anderson's body, leaving his ravaged torso lying on the ground, and Alucard removed the last of the Nail's influence by crushing Anderson's heart in his hand. Unable to live without the power of the Nail holding him together, Anderson crumbled apart into dust after a final conversation with his old nemesis.

It is unclear what happened to Helena's Nail after Anderson's death. It was last seen falling to the ground after Alucard crushed Anderson's heart - presumably, either Hellsing or Iscariot forces retrieved it after the battle.

Powers

 * Holy Touch: Being a nail used to crucify Jesus Christ himself, Helena's Nail is one of the holiest artifacts in Christianity, and this holiness is extended to anyone who fuses with it. The slightest touch from a Nail-infused person inflicts heavy damage on demonic entities such as vampires, even causing flames to erupt at the point of contact. It is possible that this is what allowed the vines to tear through Alucard's shadow constructs.
 * Enhanced Speed: While imbued with the Nail's power, Anderson appeared to have gained some measure of superhuman speed beyond what he had previously, managing to repeatedly strike Alucard before the vampire could react.
 * Vine Manipulation: A person who fuses with Helena's Nail can generate and manipulate a seemingly-endless supply of thorny, vine-like tendrils. The vines appear to spread from the nail itself, rapidly replacing most of the host's body mass. These vines can be used offensively to whip, impale, or bind opponents, or defensively to block incoming attacks. During Anderson's final battle with Alucard, the vines he manifested proved agile enough to block a bullet fired at relatively close range from hitting the exposed Nail in Anderson's chest. At one point, Anderson also used his vines to wield a dozen of his bayonets simultaneously.
 * Regeneration: While implanted with Helena's Nail, Anderson's regenerative abilities were augmented even further than normal, being comparable to Alucard's normal rate of regeneration. Any damaged parts of his body were quickly replaced with vines that gradually reformed his natural appearance, although the latter effect was noticeably slower than the former. Combined with the natural strength and speed of the generated vines, the host of Helena's Nail is almost impossible to defeat through physical damage alone; notably, its power allowed Anderson to rapidly heal from damage inflicted by Alucard's Jackal, which was specifically designed to counter "Regenerators" like Anderson.
 * Weapon Enhancement: The Nail's powers appear to extend to the user's weapons as well as their body. When Anderson used his bayonet to impale Alucard, vines sprouted from the wound before bursting into flames.

Weaknesses

 * Loss of self: Once Anderson fused with the Nail, he became a completely different person, as noted by Heinkel Wolfe and Yumie Takagi. He did not speak and simply attacked blindly while under its influence, implying that the Nail may have suppressed his higher thought processes.
 * Reliance on the Nail: If Helena's Nail is removed from its host, they automatically lose all of its powers. It is also heavily implied that removing the nail is fatal to the user, as its generated vines make up most of their body once implanted. This weakness is further expounded by the fact that Helena's Nail remains visibly protruding from the user's chest once implanted, although it gradually burrows further into the body. Removing the nail restores the user's humanity, however, in the short time that they have as they are dying.

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.).
 * When Anderson reveals the Nail of Helena, Alucard mentions other holy relics; the Shroud of Turin, the Holy Grail, and the Lance of Longinus. It is unclear if these artifacts also exist in the world of Hellsing, and what powers they would possess.
 * The thorned vines growing out of Anderson's mutated body may be a reference to the Crown of Thorns, which was placed on Christ's head before crucifixion. Also, the thorns may represent life, contrasting Alucard's association with death.
 * Anderson's appearance as the "Monster of God" is somewhat inconsistent. Notably, his face changes several times, including a mass of vines emerging from half of his head (with his remaining eye being blank and white), a thick ball of vines in the shape of a basic human face (with indentations for the eyes, nose, and mouth), and vines perfectly mimicking the contours of his face, (with Anderson's eyes and teeth visible amid them).