Ea, also known as the Sword of Rupture, is the most powerful of all mystical weapons called Noble Phantasms in the Fate universe. It belonged to Gilgamesh and it is contained within the Gate of Babylon. Unlike all of his other nameless weapons that were passed on to other wielders over the course of history, it is a sword only Gilgamesh possesses that is suited only for a ruler's use and makes him transcendent. It has quite an abnormal shape that does not match what would normally be classified as something specialized like a sword. While it has a grip, handguard, and is the same length as a longsword, the section that should contain a blade deviates from the normal form of an edged weapon. The "blade" itself and the tip of the sword, spun in a spiral shape, are dull. It has the shape of a cylindrical, drill-shaped pillar made up of three independently rotating segments engraved with crimson cuneiform lettering that spin slowly in alternating direction like querns, the middle segment spinning clockwise and the top and bottom segments spinning counterclockwise.
Ea is something that was born before the appearance of the concept that the world calls a "sword", so it is not something that can truly be called a sword or have the shape of any known blade. It can be used as a close combat slashing weapon wielded much like a regular sword as shown in Fate/unlimited codes, and even with its dull tip, it is able to pierce directly through Rider's chest and slowly grind at his vitals inside. He is also capable of surging its power to wipe out enemies around him with a great storm. Rider comments that the nature of the sword becomes more absurd as he views its power. While Shirou Emiya is capable of determining every single Noble Phantasm from a vast number of different legends and origins brought forth from the Gate of Babylon, he is unable tell the nature of Ea. Its overall design is modeled after a bedrock drill used to dig undersea tunnels that looks as if were crossed with a spear. It has been given multiple gears to dig a gigantic hole as if the three separately spinning parts were eating at the bedrock little by little.
Gilgamesh considers it his greatest and most trusted treasure next to Enkidu, only using it against those he deems worthy of facing it. While he uses it against Shirou simply for the fun of showing off his treasure, he claims that he does not want to sully the sword against a lowlife for when he uses it against those he truly recognizes as fitting. He claims that only Saber and her Excalibur are worthy of fighting it during the fifth Holy Grail War. Rider is accepted as a worthy opponent during the fourth Holy Grail War, and Ionioi Hetairoi is considered a stage befitting its usage. He becomes enraged when his previous master, Tokiomi Tohsaka, even suggests that he use it to vanquish the creature summoned by Caster through the use of Pretali's Spellbook, and he abhors the thought of having to seriously use it against Shirou for a second time once inside Unlimited Blade Works. He greatly admires the weapon and often speaks to the Noble Phantasm as if it were a living being. During a once in a lifetime whim to not hold back his treasures while fighting the creatures spawned from Avenger during Fate/hollow ataraxia, he comments to it that it has an ugly job in destroying them, but its duty as a forerunner is to bestow upon them one lesson.
The sword itself is nameless, and it is the only sword that does not exist in the current world. It is something that does not appear in any modern legends, crystallized during the Age of Gods at the beginning of the world. It is the primordial sword that is the actualization of the works of a god recorded before humanity came into being, and it is that which divided the formless into a distinct heaven and earth in ancient Mesopotamia. It is a divine weapon constructed by a god with material components that have no origin on the mortal plane, and it is one of the few weapons unable to be analyzed or reproduced by Unlimited Blade Works for that very reason. Simply looking upon the weapon causes Shirou's senses to completely cease, and it makes even the greatest Noble Phantasms look like third-rate weapons. The names given to the sword and its ability by Gilgamesh are thought to be references to the Great God of earth and water, Ea, of the Mesopotamian and Babylonian myths and the Genesis Epic of the Babylonian myth, Enuma Elish.
Gilgamesh claims that the sword "knows the truth" of the world where it once existed, and by using its power, it is able to bestow its knowledge upon others. As it is once referred to as "The Sword That Cut the World Apart", he calls it “something that knows the hellish planet before genesis”, the planet's primordial form before heaven and earth were split, that was a land filled with naught but lava and gas and a hell of scorching heat and intense cold. Referring to it as hell, Gilgamesh states that it is source of all legends of lands of the dead. The memory of the time before the existence of the planet, a place and time when organic existence had been impossible, is something possessed by all organisms, but it is no longer found in the imaginations or spoken memories of people. It is the first memory of life that is a genetically inherent and repressed knowledge which can only be shown to those looking upon the sword. The weapon "Slash Emperor" used by Ado Edem is also capable of showing a "Truth" similar in nature to that shown by Ea. In the desolate Land of Steel, it gives a glimpse of the blue sky of the previous world during the Age of Man.
Unlike most other Noble Phantasms, the ability of the sword has its own unique name instead of simply chanting "Ea" to use its function as a Noble Phantasm. The attack, known as Enuma Elish: The Star of Creation that Split Heaven and Earth, signifies the state under which it releases maximum output. Upon activation, the triblade segments of Ea gradually begin to rotate faster with each revolution, acting in concert with the movement of the Heavens. As they begin rotating rapidly, each creaking with weight and power equivalent to tectonic movement, they create a shrilling howl once Gilgamesh commands it to "wake up." Whereas Excalibur releases air outward like a whirlwind, Ea begins to swallow, compress, and accelerate wind pressure into a storm of wind and light on the same magnitude as Excalibur. The generated wind pressure strata simulates spatial rends to create an artificial space-time dislocation that acts as a crushing torrent capable of pulverizing any opposition. The actual output of the attack equals or slightly surpasses than that of Excalibur, but the swirl of air behind it and the enormous amount of seething and overflowing prana within it are on an entirely different level beyond measurement.
While he doesn't exhibit the ability during Fate/stay night due to holding back, he displays the true nature of the weapon by truly going all out during hollow ataraxia and Fate/Zero. Showing its power as an "anti-world" weapon, it attacks everything in sight with a single strike. It cannot be said that what the blade cuts down is limited simply to "the enemy", as it is not matter of aiming it, and it is impossible to even discuss as to whether it will hit its target or the practicality of the force behind it. Grinding at the laws of space with its power, it creates a rip in space that extends from not only the earth, but also to the sky and atmosphere. It is a crack that distorts space to pierce the very nature of the World itself to show the "Truth." All that used the cut space as a foundation is swallowed and crushed by the void, and the dazzling light only continues to grow as it continues to complete the destruction. Its use in a fight is not something that can be called a battle, but rather the wrath of nature itself.
Preforming the miracle of genesis, the attack opens an abyss capable of crushing all of creation, and the center of the storm is not calm, but rather a hole to hell itself that returns all that enters its realm to the nothingness from which it originated. The wind pressure creates a vacuum that takes all things with form, the land, the atmosphere, and the sky into the whirling void. The tumult of genesis takes everything that was nothing more than chaos which could not form any meaning, and creates a new truth that divides and distinguishes Heaven, Sea, and Earth. Within the darkness where everything is returned to nothingness, only Ea is left to shine with brilliance like a star of creation amidst the destruction, the first thing illuminating the new world. The ability takes the entire world within the Reality Marble Ionioi Hetairoi, and cracks, shatters, and collapses it into the abyss like the ending of an hourglass. The entire world would have been completely destroyed had it not collapsed on its own due to a lack of energy.
The attack power is based upon twenty times Gilgamesh's strength statistic with a possible boost by adding his magic statistic to his strength statistic at random. The maximum output of the sword is four thousand damage, compared to an A+++ Noble Phantasm outputting an attack power of two hundred. This number can be further increased by the amount of wealth of Noble Phantasms contained in his treasury with more wealth providing more power. It can only be defended against by an elimination rank "Armor Class" statistic or by being nullified by a counterattack with an equivalent level of power. Excalibur is unable to match it, and Saber is only able to push it back for a brief moment, creating a boundary in space, even if she puts everything into the strike and stakes her life on blocking it. She comes out of the attack extremely injured and unable to act for a period of time until she heals. Rho Aias projected by Archer is able to protect Shirou while Gilgamesh is holding back, but he still receives grave injuries. Avalon is the only defensive ability shown to completely defend against it, something which Gilgamesh truly thought to be completely impossible.