Ix

The Transcendent Holy Demonic Dragon Sword Ix(超越聖魔龍剣イクス; Chōetsu seimaryu Ken Ikusu), sometimes somanized as just IX is the exclusive sword of Ichijou Tsukino from Highschool DxD: Яe-birth after the events of Volume 9.

Being the fusion of the Holy Dragon-Slayer Sword Ascalon and Rhongomiant, plus Ichijou's and Yagura's own energy mashed together into the blade, Ix is considered a physical aberration that it shouldn't possibly exist even in the realms of the current reality, thus receiving the exclusive classification of Transcendent Sword(超越剣; Chōetsu ken). Since it has the power of both Ascalon and Ichijou/Yagura, it has the power to slay dragons, holy creatures and devils.

Summary
First created during the events of Volume 9, Ichijou would contact the spirit sealed inside Rhongomiant, the Seraph-level angel Ophelia, and ask for her to let him control Ascalon and repair Rhongomiant itself, which has been broken after Ichijou's confrontation with Evelyn Livan Lucifer. While Rhongomiant was indeed broken and beyond any form of possible repair, Ophelia said that with her ability to link the hearts of others and Ichijou's and Yagura's powers combined, they could not only fuse both swords and enable Ichijou to fully control Ascalon's holy dragon-slaying abilities, but also transcend the boundaries of this dimension and create something the world has never seen before. Thus a holy demonic dragon Sword was created, allowing Ichijou to finally stand against a rampaging Evelyn.

After the confrontation, the Demon Lord Mary Beelzebub would try and fail to analyze the sword, classifying it as a new type of magical sword which couldn't ever possibly exist even in the timeline the story takes place, calling it an abomination of transcendent existence and a Chimera of mixed powers. After retrieving back, Ichijou decided to call it Ix since both his and Yagura's energy were used and fused to create it.

Appearance
Ix takes the shape of an oversized khyber knife with only one white edge and a dull and slightly curved grey opposite side, which consists of parts of the blade of both Ascalon and Rhongomiant, respectively, a silver chain that represents Ophelia's power to "bind two hearts together" linking them. There's also a smaller, black blade that comprises the inner part of the sword and a hilt-less grip, which both represents Ichijou's and Yagura's energy combined.

Abilities
"I'm not complimenting you, Red Dragon. This sword has reached a realm beyond anything this universe has ever seen."

- Mary Beelzebub According to Mary Beelzebub, one of the current Demon Lords and the Chief Advisor for the Technology Department in the Highschool DxD: Яe-birth continuitity, Ix is an abomination with no possible way to exist even with the death of the Original Four Demon Lords and God from the bible and the new reality of the current timeline, calling it a sword that transcends everything known by any faction up to this point and a Chimera of merged powers that could never do such thing, yet are in complete harmony in it. Ix's existence is so alien that no one can feel any presence coming from it, and as such it can't be detected or discerned by any angel, devil or even God. Mary describes this phenomenon as "two-dimensional minds unable to understand a three-dimensional object".

Being the result of merging Ascalon, Rhongomiant and both Ichijou's and Yagura's demonic powers, Ascalon has the properties of a demonic, holy, dragonic and dragon-slaying swords, and as such, it has the ability to slay devils, angels and dragons, while also being able to channel Ddraig's powers into the edge and give his dragonic properties and abilities to it, such as [PENETRATE]. All those abilities, that should never be able to co-exist in a single thing, being controlled by the spirit of Ophelia residing inside of it. Because of this, Ix cannot be considered just a holy sword, a demonic sword, a dragon-slaying sword or even a holy demonic sword, thus receiving the exclusive classification of a Transcendent Sword(超越剣; Chōetsu ken). It is noted by Mary, however, that while the properties and origin of the sword are indeed impressive, due to Ichijou's underdeveloped demonic powers, Ix cannot reach it's full potential yet.

Cross Blade Dragonar
Cross Blade Dragonar, also Known as "Dragon's Fang that pierces the heavens", is an ability in which Ichijou can fire a beam of energy that enhaces Ddraig's [PENETRATE] ability, serving also as a ranged attack. Using Ix, Ichijou is able to use Crimson Moon Dragonar(, lit. Moon-shaped Streak of the red Dragon Emperor) an enhaced, massive, moon-shaped slash of demonic/holy/dragon-slaying/dragonic power that not only causes severe damage for both angels and devils, it's also practically indefensible. However, the amount of energy it takes to use it is extremely highly.

Trivia

 * The image that Ix is based on is from Tensa Zangetsu and it's Getsuga Tensho ability from Bleach.
 * The name Ix is a reference to Ix Gremory, the protagonist of the spin-off story Highschool DxD: EX and the Son of Rias Gremory and Issei Hyoudou.
 * The name is also a reference and a pun on the roman number IX(9), Ichijou's and Yagura's name and the fact that both their powers are merged inside the sword. Thus 1(The "Ichi" in "Ichijou" read as "一", "one") plus 8("Ya" can be read as "八", which means "Eight") equals "9"(IX in roman numbers)
 * Despite not having a presence, Ix curiously has a smell, which it descibed as "Strawberry shortcake" and "strawberries". Much to Ichijou's dismay, it's the same smell of Serena Sitri's and Berolina Gremory's lipsticks, respectively.
 * According to Mary Beelzebub, only the heavenly dragons have enough power and compactibility to touch and use Ix, meaning that Elizabeth can also used it at will.