The Black Blades (黒鉄之刃, Kurogane no Yaiba?) are an organization in Bravely Default and Bravely Second: End Layer, the first division of the Eternian forces. Notable members include their commander, Nobutsuna Kamiizumi, and officers Hayreddin Barbarossa, Konoe Kikyo, Praline à la Mode, and Qada. In Bravely Second, Kamiizumi, Kikyo, Praline, and Barbarossa resurface as optional opponents.
The Black Blades, under the command of Nobutsuna Kamiizumi, is one of several legions working towards the spread of Anticrystalism among the citizens of Luxendarc. As the elite legion of the duchy, the Black Blades were also given humanoid dragon soldiers developed by duchy. When the civil war in Eisenberg began, the Black Blades were deployed to support the Swordbearers, as the Shieldbearers were Crystal Othrodoxists and outnumbered them, with Barbarossa supplying the faction goods by sea. But the Black Blades faced drawbacks during their initial involvement in both their dragon soldiers escaping to the wilderness to Qada acting against orders to release a powerful poison to kill a great number of people on the battlefield. While this toxin killed hundreds of thousands of Shieldbearers, it also affected Swordbearer troops and left that area of land uninhabitable for years.
By the events of the game, as Kamiizumi briefly returned to Eternia to test his pupil Edea Lee when she is assigned to the Eternian Sky Knights, Konoe Kikyo used the passageway under the Eisen Bridge in an attempt to capture the fire vestal but ended up killing her when she resisted. A volcanic eruption occurred soon after which blocked off the entrance to the Temple of Fire, forcing the Black Blades to attempt to find other ways into the temple. By this time, the Black Blades aid the Swordbearers in kidnapping orphaned boys to mine mythril in the Mythril Mines as canary boys.
By the time the wind vestal, Agnès Oblige, and her allies reached Eisenberg, the war was seemingly at a standstill. Konoe was unsuccessful at finding a way to enter the Temple of Fire, while the main battle was ongoing due to the Shieldbearers' strong defense of the main bridge with Praline à la Mode deployed to aid the Swordsbearers with her empowering music. After realizing that the Fire Crystal was blocked off, Agnès and her allies chose to assist in the war efforts, hoping to find a way into the Temple as time went on.
During this time, each of the Black Blades officers would be forced into battle against the vestal. Praline abandoned her post after her singing is drown out while Qada, assigned as field medic, was killed by Kamiizumi when he realized the scientist is too dangerous to be allowed to leave Starkfort alive. Agnès's group also defeated Barbarossa and then Konoe when she attempted to assassinate the Shieldbearers' commander Daniel Goodman. As the war's tides turned in favor of the Shieldbearers with the Swordbearer leadership abandoning Starkfort, Kamiizumi faces the group and Edea and is defeated while pleading with his student to consider her actions. With the Black Blades effectively neutralized, the tide of the war turned clearly in favor of the Shieldbearers, and began to draw to a close. After the events of Bravely Default, with their purpose in Eisenberg no longer needed, the surviving Black Blades disband and go their separate ways.
Other versions of the Black Blades exist in parallel worlds, usually with the same goals and fates. In the fifth world, Agnès and her party face all the Black Blade's officers, barring Kamiizumi, at their headquarters. However, the Black Blades quickly retreat to Eternia, where they intended to face the vestal and her allies in a final battle to test their resolve.