Rho Aias: The Seven Rings that Cover the Burning Heavens (熾天覆う七つの円環, Shiten Ōu Nanatsu no Enkan?) is the shield used by Aias the Great and the only shield capable of stopping Durindana of the great hero Hector. It was a bronze shield covered in seven layers of oxhide, which the aforementioned javelin, having never before been blocked during the Trojan War, pierced to the seventh layer before stopping. Its existence was sublimated into a Conceptual Weapon that is said to be an absolute defense against any thrown weapon.
Archer came in contact with Rho Aias: The Seven Rings that Cover the Burning Heavens (熾天覆う七つの円環, Shiten Ōu Nanatsu no Enkan?, localized as 7 Rings of Heaven) at some point in his life, and added it to his library of weapons and defensive armaments stored in Unlimited Blade Works.
In its greatest form, it is said to be seven flower petals made from light. It takes the form of a seven layered Bounded Field in the shape of an iridescent flower in reference to the rocket larkspur (Consolida ajacis) flower that bloomed from Aias' blood as he died, with seven petals representing the seven layers of oxhide. Each flower petal layer has the defensive power of a fortress wall, and Archer cannot personally recall any thrown lance that would be capable of penetrating even the first layer. It is necessary for its user to provide constant magical energy to form the shield.
He uses it as his main defense as it is the one in which he has the most proficiency with, and Shirou Emiya cites it as Archer's greatest protection. He uses it to defend against Cú Chulainn's Gáe Bolg which manages to pierce up to the seventh layer before finally stopping. This action takes much of his energy as it takes three times the amount of magical energy as a weapon in order to project it, and still leaves his arm and body damaged afterward. He can also project it from a distance, allowing him to shield Shirou from Gilgamesh's Enuma Elish without either of them realizing it. If it is used by Shirou after having access to Archer's knowledge, he is only capable of generating four petals in the Heaven's Feel route and Fate/hollow ataraxia. It is still powerful enough to help Bellerophon overpower Excalibur Morgan and temporarily deflect a charged shot of Hrunting. Shirou is able to project the full version during Unlimited Blade Works after "pulling it from the hill" of the Reality Marble in order to protect himself from Gilgamesh's onslaught of swords.
In the alternate universe of Fate/kaleid liner PRISMA☆ILLYA, in the alternate dimension of the Ainsworth, Shirou does get Rho Aias at some point in time. He used it to protect Rin Tohsaka, Luvia Edelfelt and Bazett Fraga McRemitz from a massive ranged attack by the Grail mud-born 'heroes' who were under the control of Julian Ainsworth. Kuro can also actualize Rho Aias, albeit with only four petals.
 Fate/Apocrypha material - Encyclopedia: Aias [Person's name], p.148 [T]
Aias [Person's name]
A hero who fought alongside Achilles during the Trojan War. There is both an Aias the Great and an Aias the Lesser, but neither of them met a decent end. The shield of Aias the Great is the famous “Rho Aias: Seven Rings that Cover the Fiery Heavens”.
 Fate/complete material III: World Material - The Servants of the Fifth Holy Grail War: Archer, p.026-027 [T]
Master: Tohsaka Rin
Alignment: True Neutral
Noble Phantasm: ??
Life as a Human
This is Emiya Shirou after becoming a Heroic Spirit in the future. He stubbornly trained himself after the Holy Grail War, and pursued the dream of becoming a superhero. However, he soon fell into despair as he realised that his own power was insufficient to save mankind. Before the dying people, Emiya made a pact with the” World” and become a hero that can produce miracles, yet he died a tragic death because of the betrayal of his allies. Although he died of betrayal, he did not hate mankind. However, the “World” ironically gave him the duty as a Heroic Spirit “to slaughter all humans at a particular location when mankind is at the threshold of complete self destruction” --- a “Counter Guardian”.
Since Emiya is a Heroic Spirit from the future, he does not have any blessings provided by fame. In addition, he does not have Noble Phantasms, as a result his basic abilities are below other Servants. However, his exceptional use of tactics and battle experience makes his combat style very distinct from other Servants. The Archer class originally focuses on long range combat, but Emiya loves melee combat and wishes to conceal his trump card, thus he focuses on melee tactics with Kansho and Bakuya when engaging other Servants.
The reason an Emiya with no Noble Phantasms is able to match other Servants or even exceed them is the Reality Marble “Unlimited Blade Works”, which includes “all the elements necessary to shape swords”. This Boundary Field can copy weapons that are seen only once, and store them within. In the Fifth Holy Grail War, the weapons stored had exceeded thousands. Emiya can freely take out and utilise the weapons according to the situation, and he can also assault the enemy by firing many Noble Phantasms from the Boundary Field like arrows in the same way as Gilgamesh’s “Gate of Babylon”.
Emiya’s trump card is firing copied Noble Phantasms as arrows – “Broken Phantasm”. On impact, the magical force will explode, generating overwhelming destructive power. By assaulting melee Servants with this type of long range attack, Emiya is able to turn the odds to his favour.
Magic Resistance: D
Emiya’s Magic Resistance is weak. Its rank is D, in other words, spells more than one bar will annul this resistance. The benefit it provides is equivalent to an anti-magic amulet. This level of resistance can be easily overcome by a relatively strong magus.
Although Emiya was a magus during his life and possesses unusual Projection sorcery, his affinity with “sorcery” is much worse compared to Heroic Spirits of ancient times who saw sorceries and True Magics as commonplace. The level of Magic Resistance is a result of this.
For Emiya who possesses low Magic Resistance, it is easy to picture the kind of effects great sorceries and ritual spells can have on him. Even spells greater than two steps can be lethal to him if hit. Because of this, Emiya is at a disadvantage against Caster, who has powerful sorceries at her disposal. Depending on the situation, Emiya may even have to pay attention to the attack of Masters who are magi.
Independent Action: B
Normally if a Servant loses his Master, he will disappear within hours if he cannot replenish the mana required to remain in this world. The amount of time each Heroic Spirit has before disappearing varies, but Emiya can remain in this world for 2 days due to Rank B Independent Action. However, this is the ideal value achieved by maximally conserving mana and avoiding battle and Noble Phantasm usage.
In UBW route, Emiya’s Master switched from Rin to Medea, and after Medea’s death, he continued to operate independently and battled Emiya Shirou. Through all these events, one is able to recognise Emiya’s ability to survive alone. In addition, even if Emiya’s spiritual core sustained lethal damage, he can still survive for a short period. This ability is the reason why Emiya is able to secretly observe Shirou and gang’s battle as a spiritual body after being defeated by Shirou. In addition, after the battle between Shirou and Gilgamesh had concluded at Ryudo Temple, Emiya appeared in front of Gilgamesh as he attempted to pull Shirou into the darkness. He shot an arrow between the eyes of Gilgamesh and sent him alone into the darkness. The arrow shot at that time was a regular arrow, and from the fact that Emiya gradually began to disappear after this attack, this is probably the limit of Emiya’s materialisation.
The visual ability that is also called “Eagle Eye”. This is a must-have ability of the Archer Class. It is also frequently used during scouting. Simply looking from a high location is sufficient to fully survey the town and search for enemies. In addition, Clairvoyance will affect the accuracy of bows. Also worth mentioning is that, as Emiya readies his bow, he will be able to precisely snipe even enemies moving at high speeds as long as they are within a 4km range.
Archer, who possesses Clairvoyance, is able to execute “ultra long-range sniping” with accuracy transcending the realm of men.
During his life time, the sorceries learned by Emiya are unremarkable. Before becoming a Heroic Spirit, even “reinforcement” was quite difficult. However, the “projection” sorcery he wields is quite special, as it is able to duplicate weapons, including all the components, to near perfection. In addition, during duplication, he can even read the wielder’s skills, which allows him to gain all kinds of Noble Phantasms and combat skills.
During his life time, Emiya used the preliminary step of projection – “structural analysis”, to find the location of an item’s fault and proceed with repair.
Eye of the Mind (True): B
A danger-avoidance ability that utilises the intelligence collected up to the current time as the basis, in order to predict the opponent’s activity and change the current situation. This is not a result of talent, but an overwhelming amount of combat experience. A weapon wielded by none other than a mortal, gained through tenacious training. Using Eye of the Mind, Emiya was able to successfully counter Cú Chulainn’s thrusts that were invisible to the eye.
Even with Rank B Eye of the Mind (True), Emiya was unable to see through Emiya Shirou’s passion-infused strike which put “ideal” on the line.
Unlimited Blade Works
Maximum Targets: ???
The “Innate Bound Field” wielded by Emiya. It is his ability as a Heroic Spirit with no Noble Phantasms. The inside of the reality marble is a world like a steel mill, filled with weapons, flames, and giant gears. The uncountable swords plunge into the ground and were preserved thus. The majority of the weapons persevered in the reality marble are Noble Phantasms of Heroic Spirits copied through projection sorcery, each possessing deadly powers. Although the majority of the weapons are swords, the Noble Phantasm that provides absolute defence against projectiles, “Rho Aias”, is also said to be copied and stored in the reality marble. Also, the ability of the replicated Noble Phantasm suffers one rank down compared to the original.
Not only can Emiya freely access the weapon stored inside Unlimited Blade Works, he can also modify the weapons to his wish like Caladabolg II. In addition, he is able to capitalise on his ability to repeatedly project: use Noble Phantasms as disposable arrows, and then unleash the magical energy stored within – the tactic called “Broken Phantasm”.
The shield used by the hero of Trojan War, Aias. The Boundary Field Noble Phantasm that provides absolute defence against projectile weapons.
Kansho and Bakuya
The famous swords of Chinese legend. The Yin-Yang, Female-Male paired swords based on the Yin-Yang Doctrine. Emiya’s favourite melee weapons.
The legendary sword “Caladbolg” of the Ulster Cycle, projected and modified by Emiya. Not very useful as a sword, but rather used as an arrow for “Broken Phantasm”
 Fate/complete material III: World material - FAQ with Nasu: General Questions about Fate, p.130
Q: In the end of the Rin route, was it Shirou that projected Rho Aias in the Shirou vs Gilgamesh fight?
Q: In the end of the Rin route, was it Shirou that projected Rho Aias in the Shirou vs Gilgamesh fight? Or was it Archer? In "Fate/side material", it's said that it was projection magic from Archer, but in the story, there was the depiction of Shirou "pulling the shield from the hill". Does this mean that this switched to Archer's scene?
A: This has been easy to misunderstand, but the part about Archer supporting Shirou was the time before Shirou pulled out Rho Aias, before Shirou came to his realization. After Shirou's monologue about his surprise that he was still alive after taking Gil's attack, "If I survived, there must have been a reason why I survived. But that was simply something I didn't have any control over." That was the "Rho Aias" that Archer made to help Shirou in a way that wouldn't let Gilgamesh know there was someone else waiting to ambush him.
 Fate/side material - Encyclopedia: Rho Aias [Noble Phantasm], p.078-079 [T]
Rho Aias [Noble Phantasm]
The Seven Rings that Cover the Fiery Heavens.
In Greek mythology, the shield used by the hero Aias during the Trojan War.
It was a bronze shield covered by seven layers of ox hide, and the only thing that proved capable of stopping the javelin of the great hero of Troy, Hector. (Though it managed to penetrate six layers of ox hide, the seventh layer was unbroken.)
Afterward, its fame spread, and its existence was eventually sublimed into a "conceptual armament" boasting absolute defensive power against thrown weapons.
It is the only defensive armament Archer can use proficiently.
The Rho Aias that protected Shirou's spellcasting during the finale of the Rin route was not something he projected himself, but was actually made by Archer who was watching the battle from a distance.