Dante (Devil May Cry) wields the Rebellion, a magical sword that was given to him by his father, The Dark Knight Sparda, and which serves as a physical manifestation of his power.
Being the son of Vergil, Nero (Devil May Cry 4) is able to wield his weapon, the katana Yamato.
The Devil Arm Lucifer (Devil May Cry 4) manifests a slew of volatile energy rapiers Dante can guide with a gesture.
The Dark Knight Sparda (Devil May Cry) is a legendary demon who once wielded the weapon named after him, an indestructible sword imbued with his own demonic power.
Janemba (Dragon Ball series) wields his Dimension Sword...
...Given that it was created by him, the sword was capable of unleashing powerful energy slashes, cutting through virtually anything, and opening dimensional portals.
Inuyasha (InuYasha) wields the Tessaiga, a powerful blade that was created from the fang of his father, the Inu no Taisho. It possesses an Anti-Yōkai Barrier that prevents any demon other than Inuyasha from wielding it, and can kill 100 demons with its signature Wind Scar.
Sesshōmaru (InuYasha) wields the Tenseiga, a sword that was also once a part of the Tessaiga. However, unlike the Tessaiga, the sword could not kill, but rather ressurect 100 beings in one swing. Despite this, it is able to kill beings who were not from the world of the living, such as spirits, hellhounds, and the undead.
Alongside the Tenseiga, Sesshomaru wielded Tōkijin, an incredibly powerful sword forged by Kaijinbō from the fangs of Goshinki. The sword possessed strength and ablities that rivaled those of his brother's, Inuyasha, Tessaiga, but it eventually was destroyed in the battle against Mōryōmaru.
However, when Sesshomaru regained his left arm, he also gained the more powerful Bakusaiga, which serves as the physical manifestation of his own power and is ten times stronger than the Tessaiga.
Doku (Ninja Gaiden) is a powerful lord of the Great Fiends of Vigoor Empire who wields the Dark Dragon Blade, a weapon that was carved from the bones and infused with the soul of the Dark Dragon. With each person slain by it, its power grows.
Doku (Ninja Gaiden) also wielded the Kitetsu, a cursed Tachi that feeds on the souls of those slain by its blade.
Genshin (Ninja Gaiden) is a powerful and ruthless ruler of the Black Spider Clan who wields the Blade of the Archfiend, a weapon that possesses the magic of the Arch Fiend, Vazadah and is as powerful as Ryu Hayabusa's True Dragon Sword.
Akujiki (Shinobi) is a powerful demonic sword wielded by the leaders of the Oboro Clan. It feeds on the Yin of defeated enemies and converts it into cutting power, and if left unfed, it will drain the life and soul of its wielder.
Demise (The Legend of Zelda: Skyward Sword) carries a powerful sword that is actually the true form of his underling, Ghirahim. The sword rivals that of Link's Master Sword in both magic and appearance.