Cross

A Cross (十字) is a symbol consisting of two intersecting lines or bars, usually perpendicular to one another. It is also a term used for symbols based around the shape and objects in that shape.

The shape has various associations in belief and religion, with a cross being the primary symbol of Christianity, representing the cross on which the Son of God died. With its associated meanings, the cross also plays an important role in various forms of magic.

Etymology
The term cross, as referring to the tool of the crucifixion, arose in Late Old English in the 11th century, with the non-religious intersection meaning apparently arising in the late 14th century. It is likely derived from similar terms in Old Norse and Old Irish, in turn ultimately derived from the Latin crux. The previous term used for the instrument in Old/Middle English was rood.

Principles
The cross is the primary symbol of Christianity, representing the cross (known as the True Cross) on which the Son of God died during the Crucifixion.

Besides the Son of God, many saints are also associated with crosses, with some of the early martyrs being crucified in a similar manner, though a number chose to die on a different type of cross (considering themselves unworthy of dying in the exact same way), such as St. Peter and St. Andrew, with these crosses becoming their symbols.

Crosses are featured in the flags of various countries (including those of the United Kingdom and the four comprising it), heraldry, and in magic circles and symbols, including the Banner of the West, a prominent symbolic weapon in modern Western magic.

Aside from being separate symbols or components, crosses act as joints in a battle formation, and intersections in magical symbols. They can be used to gather, direct and scatter power, and when properly used can interfere with and turn the power of an opponent's spell against them. One magician who uses crosses primarily in this way is John William Brodie-Innes (or at least his reproduction), who makes use of sparks produced by striking the ground with his metal-soled shoes to form the shapes of various crosses, being able to weave greater formations the more time he is given.

Like the Sephiroth, the cross is a symbol which corresponds to the human body and can be utilized in magic as blueprint for the body and soul.

Index Arc
A cross was going to be used in the process of erasing Index's memory.

Deep Blood Arc
Aureolus Izzard was noted to have used a Germanic Cross and basic materials, making a soul, in the creation of the dummy version of himself.

Kazakiri Hyouka Arc
The construction of Sherry Cromwell's Golem Ellis incorporates the image of the Cross, with the head, right arm, left arm and legs, with each side assigned with the power of the four Archangels associated with the cardinal directions.

Orsola Aquinas Rescue Arc
During the incident surrounding Orsola Aquinas and the Book of the Law, the crosses worn around many necks and in most churches symbolizing the cross on which the Son of God died and able to possess a tiny fraction of the original's power was mentioned during an explanation of Idol Theory, and variations of the cross (such as the Latin, Celtic, Maltese, St. Andrew, Patriarchal and Papal crosses) were mentioned during a conversation between Kamijou Touma and Orsola. Tatemiya Saiji wearing the red cross of St. George, the symbol of the Anglican Church, on his shirt was also mentioned, with regards to his intentions, by Kanzaki Kaori when talking to Touma after the incident.

Most notably, a regular Anglican cross was given to Stiyl Magnus by Archbishop Lola Stuart, which was later passed onto Touma, who then placed the cross around Orsola's neck. As the act of putting an Anglican cross on someone places them under the protection of the Anglican Church and effectively one of their own, it was used as justification for the Anglicans rescuing Orsola from the Agnese Forces, against the argument that the matter was an internal affair of the Roman Catholic Church.

Daihasei Festival Arc
The magic-related events which transpired during the first day of the Daihaseisai revolved around a notable cross associated with St. Peter, the Croce di Pietro. During these events, a misunderstanding from the sight of Himegami Aisa's Walking Church cross resulted in her being severely injured by Oriana Thomson. It was also noted that the red cross (associated with St. George and the Anglican Church) on Lidvia Lorenzetti's clothes had caused her to mistaken be for an Anglican in the past.

La Regina del Mare Adriatico Arc
Biagio Busoni had necklaces with numerous crosses and crucifixes, with his magic drawing out multiple meanings associated with them, many from the stories of saints, as the basis for his spells. A cross also acted as the core of La Regina del Mare Adriatico.

Academy City Invasion Arc
A cross on the end of a chain attached to Vento of the Front's tongue acted as the core for her Divine Punishment spell.

Document of Constantine Arc
During her interrogation by Stiyl Magnus and Agnese Sanctis in the Tower of London, Lidvia Lorenzetti used an incantation which used Agnese's cross as a conduit for a spell to destroy her bindings.

Acqua of the Back Arc
Cross symbols were used to supplement the Saint Destroyer, and in the spell Pope Matthai Reese used in an attempt to bind Fiamma of the Right.

World War III Arc
During Vento's battle with Fiamma, an anchor-shaped ice cross in place of her old one acted as the new core of La Regina del Mare Adriatico. The Star of Bethlehem was also in the rough shape of a cross.

Toaru Majutsu no Index SS: Kanzaki
During her battle with Brunhild Eiktobel, Kanzaki Kaori locked her sword with her opponent's Gungnir at an angle to form a cross symbol for a spell to raise her opponent's Saint side, thereby weakening her Valkyrie side.

Toaru Majutsu no Index SS: Necessarius Special Admission Test
During the battle at Stonehenge, Itsuwa used her blood to draw a cross on her spear handle for a spell connected to St. Andrew. After the conclusion of the whole incident surrounding their entrance exam for Necessarius, Freadia Strikers gave Itsuwa and the other Amakusas a silver and red cross rosary, symbol of the Anglican Church, signifying their acceptance.

Toaru Majutsu no Index SS: Agnese's Magic Side Work Experience
While fleeing with Angelene from the demon of the Ceremony of Ba Moun, Frau Halveria crossed herself with her fingers and invoked Baron Samedi, the Voodoo death god standing at the crossroads, to form an invisible barrier to slow the demon down.

A Necessarius magician tasked with observing the Agnese Forces wielded a censer and a cross, with Agnese noting the two as standard for an area-of-effect attack but not very flexible, guessing that he would usually be "dropped in" to crush a magic cabal on his own.

Homecoming Arc
Just like the Star of Bethlehem it was imitating, Radiosonde Castle was shaped like a cross. During her battle with Mjölnir, on recognizing her opponent's nature, Kanzaki considered the correspondence between the cross and the human body.

Coronzon Arc
During the battle with the recreated Golden Dawn, John William Brodie-Innes used various crosses formed from the sparks caused by his metal-soled shoes,  including the, the , the pyramid cross and the  among others. When the group were pursuing the British Royal Family, he made use of a modified pyramid cross to turn Cutia Virginroad's own spell against her.