Armor of Fafnir: Blood Armor of the Evil Dragon (悪竜の血鎧, Akuryū no Chiyoroi?) is an ability that embodies and re-enacts the legend of Siegfried bathing in dragon-blood from Fafnir, granting him a dragon's body with invulnerability that made all weapons ineffective against him during his life. His tall stature, slim body, and darkened skin are all proof of having been soaked in the blood. Having swallowed the blood as well, it circulates throughout his body and affects his organs, later affecting Sieg upon having Saber's heart transplanted into him. Dyed brown with Fafnir's blood and composed of dragon scales, his skin is compared to steel in strength, unable to be wounded by either weapons or magic except with the greatest of attacks. Called invincible in life until struck down by his friend, it caused him to lose the joy of battle because it did not allow him to feel the sensation of struggling against death, his body proofed against any and all attacks, making it possible to slaughter enemies without much thought like simple labor.
It is a "continuously active-type Noble Phantasm" that allows for his skin to cancel physical attacks and magic equivalent to B-rank or lower. He can directly fight those with B-rank strength like Achilles without taking a scratch, although special cases like Karna's spear can allow damage to go through. It requires attacks of A-rank and above to harm him, but attacks only register as damage only after the defensive values of an amount equal to B-rank are subtracted from them. All A-rank attacks are effectively reduced to E-rank attacks, meaning even qualifying blows directed towards vital points are rendered as minor scratches that can be healed by his Master at a quick rate. When facing Noble Phantasms, it gains defensive values equivalent to B+ rank, but the boost will not apply in the attack calculations if the attack is not used by a proper hero or the attack or Skill is imbued with the properties of "Anti-Dragon". Furthermore, given a case where he receives a blow while in a state of being purely "defenseless", defensive values also becomes equivalent to B+ rank. And in the case where he takes defensive action with Balmung to match the opponent's Noble Phantasm, the properties of the opposing enemy's Noble Phantasm will be further reduced. Due to this Noble Phantasm, his Magic Resistance Skill has been lost.
Due to a linden leaf sticking to him during the bathing process, he has a leaf-shaped mark upon his back where the blood did not touch that marks his only weakness. His back does not gain defensive values, allowing even the weakest of Servants to kill him by striking him there. He has a curse upon him that forces him to always leave his back exposed, preventing him from covering it with armor. Conceptual in nature, it would prevent even something like a spherical barrier from protecting him by opening a hole in the barrier facing his back. Should it be struck even once, it will be extremely difficult to restore him with healing magecraft. Due to his fame, it will become the primary target should his identity be found out by others, causing his Master Gordes to act with as much caution as possible to avoid revealing his identity. Despite this worry over his weakness, there are not many heroes who possess the skill to pull off the difficult maneuver of aiming for his back while fighting him.
 Fate/Apocrypha material - STATUS: Saber of Black, p.018-019
Master: Gordes Musik Yggdmillennia
True name: Siegfried
Alignment: Chaotic Good
Noble Phantasm: A
■ Magic Resistance: -
As compensation for obtaining Evil Dragon's Blood Armor this is lost.
■ Riding: B
Majority of vehicles can be ridden above average. Magical Beasts, Holy Beast rank beasts cannot be ridden.
■ Golden Rule: C-
A life in which money is fated revolve around.
Due to the Nibelung treasure promised a life untroubled by money, but Luck is Rank-Down.
■ Armor of Fafnir: Blood Armor of the Evil Dragon
Maximum number of targets: 1 person
A Noble Phantasm embodying the story of his bath in the blood of a dragon. B-rank equivalent physical attacks and magic are nullified. Attacks of A-rank and above register as damage after defensive values of an amount equal to B-rank are subtracted from them. If facing a Noble Phantasm used by a proper hero, it gains defensive values equivalent to B+. However, his back, which was not bathed in the blood, does not gain defensive values, and he is unable to conceal it.
■ Balmung: Phantasmal Greatsword, Felling of the Sky Demon
Maximum number of targets: 500 people
A cursed holy blade which had accomplished the feat of dragon slaying.
It also possesses the attributes of its origin, the demonic blade Gram, and will change attributes between holy sword and demonic sword depending on who wields it. The blue jewel of the hilt stores and preserves magic energy (true Ether) from the age of gods, and upon releasing it, emanates a twilight aura. Those with the blood of dragons take additional damage.
- Fate/Grand Order material I - Siegfried, p.052-061
- Fate/Apocrypha - Volume 1
 Fate/Apocrypha material - Encyclopedia: Saber of “Black” [Servant], p.162 [T]
Saber of “Black” [Servant]
One of the Servants of the Black camp. His true name is Siegfried. He is an undisputed great hero and “dragon slayer” who appears in the “Nibelungenlied”. His tall stature, slender body and tanned-colored skin are proof of him having been soaked in the blood of a dragon. The reason the weak point on his back is exposed is because of a “curse” that forces him to do so. It conceptually prevents him from protecting his back. Even if Siegfried were to be protected by something like a spherical barrier, a hole in it would definitely open facing his back. However, there aren’t many heroes who possess the skill to pull off the tricky feat of aiming for Siegfried’s back while fighting him in the first place.
Just as the impression of his face gives off, he is reticent, but his bearing, which overflows with dignity, makes him seem well-bred. He is the type to talk with a simple, unsophisticated tone and hold back his words to the absolute minimum needed. That is the foundation of his personality, and it deepened the antagonism between him and his Master Gordes.
Siegfried’s legend came into existence around the 5~6th century and spread to many lands. At nearly the same time as the “Nibelungenlied”, the story of the hero Sigurd, the “Volsunga Saga”, came into existence. Wagner’s opera “Der Ring des Nibelungen” is a masterpiece work that compiles these legends together.
In the light novels, Siegfried as he was portrayed in the “Nibelungenlied” forms the basic essentials of his character, and he only knows about the Norse Valkyries from second-hand knowledge.
With him possessing the noble lineage of royalty, being known for various his adventures and heroic tales and having met a tragic end, there are few heroes who are as heroic as him.
But it is precisely because he is such a heroic hero that he was unconsciously burdened by binds. A hero acts out of the supplications of the people, and therefore should not act without being asked. This is because a hero is such a being. Because they possess overwhelmingly immense power, they must not act out of their own will and try to grant their own wish. A hero is a being that fulfills the wishes of others, and must not ever tread any further than that.
When his wife and the wife of his brother-in-law wounded each other’s honor and a collision between them became inevitable, he once more granted everyone’s wish. He thought that it would be resolved if he, the cause of it all, died. In the end, it called forth even more tragedy, so it seems the curse of the Rhine gold took effect perfectly.
As a Servant, he is basically hard, solid and tough. “Armor of Fafnir: Blood Armor of the Evil Dragon” blocks all regular attacks up to B rank and all Noble Phantasm attacks up to B+ rank and, in addition, “Balmung: Phantasmal Greatsword, Felling of the Sky Demon” unleashes a wide-range attack that displays its true worth against an army. The blue jewel encased in the hilt of the sword contains prana from the Age of Gods, and it is possible to pull out the sword’s power to the maximum with just small quantity of it. During his battle with Karna, Sieg managed to use the Noble Phantasm so many times consecutively only because he continued instantaneously pulling out the sword’s power while replenishing his prana with “Galvanism”. The Servant version of Siegfried cannot instantly replenish the prana he expends, so his sword’s accumulation of prana is overwhelmingly faster than that of an average Anti-Army Noble Phantasm, though still not as fast as Sieg.
In the initial plans of the Yggdmillennia team, Siegfried would go out to the front lines and receive the attacks of enemy Servants as Vlad III’s protector. Vlad would be positioned to control the battlefield with “Kaziklu Bey: Lord of Execution”. Jack the Ripper would kill the enemy Masters and cause chaos in the enemy’s rear guard along with Frankenstein. Astolfo would guide the golems and control the situation with Avicebron, while Chiron would act as support by shooting at areas where a hole in the enemy lines could be made.
It was truly a perfect formation as an academic theory, but they were forced to tearfully change tactics due to Siegfried unbelievably leaving the battlefield before the war actually began.
- Fate/Apocrypha - Volume 2
 Fate/Apocrypha material - Encyclopedia: Blood Armor of the Evil Dragon [Noble Phantasm], p.148 [T]
Blood Armor of the Evil Dragon [Noble Phantasm]
Armor of Fafnir. The continuously active Noble Phantasm of Saber of Black, Siegfried. Negates all attacks of B rank and below.
When receiving regular A rank attacks, the armor’s defensive rank of B will be subtracted from the attack’s offensive rank of A… in other words, it will be reduced to effectively an E rank attack, but in the case of an attack by a Noble Phantasm, the armor’s defensive value will rise to the rank of B+. However, this additional defensive value will not be included in the attack calculations should the enemy use a Noble Phantasm or skill that has the properties of an Anti-Dragon special attack. Furthermore, the B+ defensive value is only applicable when he is attacked while defenceless, and the armor’s defense will be further reduced should he take defensive action with “Balmung: Phantasmal Greatsword”. When he goes all out in a defensive battle, Siegfried is effectively a moving fortress.
However, since the effects of this armor do not apply to the single spot on Siegfried’s back that was covered by the leaf of a lime tree, it becomes extremely difficult for him to be healed with healing magecraft if he is wounded there even once.