Archenemy

Archenemy (不倶戴天 Fugutaiten) is a katana.

Appearance
In the manga, Archenemy takes the form of a traditional nodachi, a Japanese longsword. Its hilt is wrapped in a dark wrapping, outlining a series of rhombs on it, ends in a light pommel and has a similarly light, mildly prominent fuchi, a metal disk separating the hilt from the handguard. The handguard itself takes the form of a tsuba, a flat plate perpendicular to the hilt, which has its two faces covered in intricate decorations, and possesses a mildly rounded, elongated shape with four points curving inwards, generating soft nooks, which make the tsuba itself vaguely reminiscent of a stylized four-leaf clover. The weapon comes with a matching saya, a lacquered scabbard, which is dark in color, ending in a light chape, and has a decorative rope tied around its middle part in a ribbon, with two edges left hanging.

In the anime, it still retains the form of a nodachi. Its hilt is wrapped in a dark red colored wrapping which features a gold pommel and studs along the hilt. One of the distinct differences is the presence of bandages at the tsuba section of the sword which wraps the sword tight to the scabbard with a white talisman that has the kanji of the word Seal (封 Fū), hanging under the stuba by a metal chain composed of two links. Additionally, the scabbard of Archenemy is now white in color with gold protector at the end which is decorated with a small gold design and a red colored rope tied in the lower section of the scabbard.

Description
Known as "The Blade of Resentment" (怨刀 Ontō), Archenemy is allegedly a fearsome weapon, Millianna went on to remark that its unsheathing could potentially cause a cataclysm. To ward off such occurrence, its user, Kagura Mikazuchi, employs it in conjunction with the peculiar Style of the Undrawn Long Sword, which allows her to make use of the weapon's cutting power without actually drawing it. Such use is shown to be highly effective, with the sheathed weapon being strong enough, in Kagura's hands, to cut down the gigantic Celestial Spirit Ophiuchus in mere seconds, something which led to the defeat of its summoner, Yukino Aguria.

When Kagura finally unshealthed it during her battle against Erza Scarlet, a single slash from it caused so much damage that annihilated an entire section of the conjured village during the Grand Magic Games. Oddly enough, Erza was able to block it nearly unscathed, with minimal effort.