Infinity (インフィニティ)

''"Infinity, Xyphira's final remnant... I wonder what can Kira do with it..." - Zenya Kanae''

 Infinity (インフィニティ) is an undescribably powerful sword crafted by Xyphira Athanea, the legendary blacksmith Deity. Long ago, Infinity's blade was shattered beyond repair from a powerful foe in the War of Gods. Using the last of his energy, Xyphira traded his own life for Infinity's existence. To do so, he split Infinity's fragments into the form of 4 lesser swords and released them into different dimensions: The Cosmic Ark, Neosius and Helora. The Fragments had no given name, as Xyphira was already dead by the time the Fragments were transformed into the form of Swords. Infinity was split into "Gekirin" (Named by Asakura Yuuki), "Universo" (Named by Geo the Earth Summoner), "Truth" (Named by Aletheia Ceraford) and "Twilight" (Named by Atria). Although the four are mere Fragments of Infinity, they are rumored to be "undefeatable in combat, however only those who have mastered their true power can continue on the legacy of Infinity". When the Fragments are combined, with the help of a deity, Infinity can be fully reconstructed as the "Immortal Blade", Infinity II. Infinity II's blade is gold in color, traces of Gekirin's sky blue, Universo's blood red, Truth's white and Twilight's black can be seen in the form of gemstones embedded into Infinity II's silver hilt. The gemstones aren't visible on the original Infinity, as Xyphira embedded the powers into the blade itself. Since the powers were embedded into blade, they amplify Infinity's blade thickness, nullifying its stabbing ability and impairing the style possibilities. Infinity II on the other hand can either use the 4 powers separately, or use them altogether as a truly undefeated blade.

Gekirin: Fragment of Energy (逆鱗)
Asakura Yuuki first found the fragment while searching for his wallet in a river. After he was crowned as the king of Dignitia, he named it "Gekirin", meaning Imperial Wrath. Soon after Kira's arrival to Regalia (Dignitia's capital), Asakura Yuuki dies in a battle with Lady Hakillika, the Liv'Ius Bandit leader. It was revealed that Asakura Yuuki ordered his beloved to put Gekirin in a case and bury it underground until Kira's 18th birthday, and it was discovered by Kira himself when he was having a picnic with Aila, Fia, Lucy, Yoake and Urufu. Gekirin pulses with all of Infinity's energy, making it the only fragment able to efficiently fight with magic. Kira, Yuuki and Aletheia have been seen using Gekirin in combat, often producing energy waves with Gekirin's slashes, giving this Fragment a unique fighting style. Gekirin is sky blue in color.

Universo: Fragment of Power (ウニヴェルソ)
Universo was a Fragment found by Geo the Elder Earth Summoner. When he was venturing in the outskirts of Neosius, he found the Fragment buried in desert sand when Terra the dragon was looking for underground creatures to eat. He named the sword "Universo" to fit his Summoner's spirit Terra (because of Terra's abnormally large size for a Summoner's spirit). Universo was the final Fragment taken by Kira, after he learns about the lore of Infinity. With the help of Zenya Kanae, Kira revived Infinity's full form and used it to defeat Geo's monstrously enormous Summoner's spirit, Terra. Universo was then returned to Geo as a fragment when he agrees to ally with Kira under Kanae's orders. Universo weighs significantly more than Infinity, making it harder to control in combat. Geo, however, can wield it with ease due to its enhanced strength. The bludgeoning weight allows him to break through most parries and shields. Universo is blood red in color.

Truth: Fragment of Speed (真実)
Said to be a legendary sword amongst humans (at least in Helora), wielded by Aletheia Seraford. He found the Fragment under a large boulder in the mountains while hunting, as he broke his previous wooden sword. Using the sword to bestow justice in the impure land of Helora, he established his own guild of knights: Blades of Aletheia. Following his death in the Battle of The Sting, Lily Rose Ceraford wanted her memories of Aletheia to linger, so she took Truth from his grave and sometimes dual-wields it with Black Lily - another great creation by Xyphira Athanea. Truth literally weighs as much as a feather, lifting it requires no effort at all, like an extension to one's arm. Allowing the one to swing it with full strength without the usual weight of a sword dragging the user's arm down. This is the primary reason Aletheia never loses a fight against any human. He's practiced using Truth for so long, that people describe his blade as a mere "illusion", as though using his bare hands to fight. Truth is white in color.

Twilight: Fragment of Fortification (トワイライト)
The second but first found Fragment in Neosius, it fell directly into Zenya Kanae's hands right after the War of Immortals. Kanae's prophecy caused her to gift the Fragment to Yugure, until it was passed down to the Darkness Summoner Atria - Kira's father. Atria was killed by Agathi Keravnous in the Struggle of Oblivion, resulting in Kira claiming both the Twilight and Gekirin fragments as his own. Enraged, Kira dual-wields the two Infinity Fragments in his battle against Agathi - even though he still lost. Angered by his loss, he swears to defeat her for the whole of Neosius. Twilight's outer surface can only be dented by an elite deity's weapon, any other lesser race has no chance whatsoever of even putting a single scratch on it, forged with an unknown Deity-made substance, its sturdiness was the main defense of Infinity. Hence Atria did not die by Agathi's hands because Twilight's fortification was weakened, but because of Agathi's superior reaction time compared to Atria's battle-worn and frail body. Twilight is black in color.

Trivia
1. Xyphira Athanea is the only blacksmith that's reached the highest class of Deities. He however is always reluctant to forge weapons for other Deities because of the War of Gods.

2. Besides Universo, all Fragments have been dual-wielded in the series. Either with another Fragment or with another non-deity-crafted weapon.

3. Infinity was shattered by the Deity of Pain, Mortus. Mortus used to wield Incardine, a one-of-a-kind weapon he forged out of the last remaining Infernite (a powerful substance found in his realm). In the battle, Incardine was also shattered by Infinity, but Mortus had no information whatsoever to split the Fragments into weapons. He was banished back to his realm, but he forged a replica of Incardine using regular graphite.

4. The scene where Kira dual-wields Gekirin and Twilight does threaten to show some similar scenes from another Anime. Kira wears full black clothing and is wielding a sky-blue and black blade, similar to Kirito from Sword Art Online. The director claims the extreme resemblance in appearance is coincidental.