When an explosion of emotions equivalent to the destruction of one’s heart is invoked a power stemming from the Curse Series is acquired. The Curse Series is loosely based on the 7 deadly sins Gluttony, Lust, Greed, Wrath, Sloth, Envy, and Pride, there is also a known 8th shield based on all of the New Seven Deadly Sins at once. Upon use these weapons corrupt the heart of their users, for example whenever Naofumi used the Wrath Shield early on he was overcome by pure hatred and barely able to keep it under control, meanwhile Ren was completely overwhelmed by the Greed and Gluttony Swords to the point of incoherently rampaging at anyone in sight with the latter. If the curse series is overcome by the user the Blessed Series is unlocked.
- Iwatani Naofumi has unlocked the Wrath Series due to the harsh treatment he experienced early on in the series due to the actions of Aultcray and Malty Melromark, and awoke it first when he was defeated by Motoyasu in a duel and faced the risk of losing Raphtalia, his only remaining emotional support. While Naofumi has shown increasing levels of control over his anger and this Curse Series due to Raphtalia, Firo and Gaeleon, it causes him to experience overwhelming levels of anger and hatred directed at his enemies, which in his perspective includes the entire world. The only known drawbacks are that all of his stats are cut by 30% except for defense after using the Curse Series arm 「Blutopfer」and, since said attack drains its user's own blood to attack, he could die from it, and nearly did the first time. The side effect for this shield appears to be the user looses the ability to love. This is reinforced then he looses his memory and the shield looses power. For a brief moment begins flirting with the women around him before regaining his shields power and memories. Later he acquired the New Seven Deadly Sins Series, which allowed him to modify his subordinates and slaves vastly moreso than before, turning the bioplant into a castle, gifting the Filorilo with the ability to fly, creating an entire species called the Raphs by cloning Raphtalia and so on, at the cost of having absolutely no defencive power of his own to speak of. This shield also turned him into a megalomaniac out to take over the world, but he remained a compassionate man to his subordinates and did nothing harmful to them despite becoming a cliched example of supervillainy, and he became completely obsessed with Raphtalia to boot. Finally, following the loss of Atlas in the Houou Campeign, Naofumi overcame his rage and unlocked the Blessed Series' Shield of Compassion.
- Amaki Ren unlocks the Greed Series and Gluttony Series after being betrayed by Malty Melromark and having all of his equipment and belongings stollen, as well as being faced with the deaths of his comrades, which he refuses to believe was his fault and blames it purely on their weakness. Using the Greed Series makes him more violent and dangerous, attacking others to steal their equipment, but using the Gluttony series makes him merderous and causes him to try killing others to gain EXP and grow more powerful. Using these swords all but turned him into a raving mess, he has since become a far more mellow person after being released from them. The drawbacks to these swords are that he can’t collect EXP nor can he hold anything worth money after using the Curse Series arms 「Guillotine」 and 「Schtarkfuaafar」. Later, when Atlas died during the Houou Campeign, he unlocked the Sword of Anger, a Wrath Series weapon just like Naofumi's Shield of Wrath, but he never used it because Naofumi unlocked the Shield of Compassion and proceeded to calmly and overwhelmingly lead their side to destroy Houou before he had the chance.
- Kitamura Motoyasu has unlocked the Lust Series and Envy Series after all of his teammates, all women, betrayed him, and Firo comforts him, turning all his lust towards her. While he doesn’t really have any problems after using them, likely because he has never used their ultimate techniques as Ren, Itsuki and Naofumi have, he sees women as pigs, litterally, and can’t understand their words which is more likely the reason he unlocked the series rather than a result of it. His lust is aimed at Firo, which is noticable even when not using this series, while his envy is aimed at Naofumi for being close to her.
- Kawasumi Itsuki unlocks the Pride Series after his bow is tampered with by Mald, Malty and their revolutionary faction. This series provides him with the ability to brainwash others into siding with him, and causes him to become even more egotistic and arrogant than he already was before. This is arguably the most dangerous case of a Curse Series going out of control as his power allowed a full scale rebellion to take place due to the exploitation of those around him. The consequence of using this series is that he becomes apathetic and loses his sense of both pride and justice, and unconditionally complies to any order he is given after he uses a multitude of Curse Series arms.