The Curse series is a series of weapons unlocked in the Legendary or Vassal Weapons based on the seven deadly sins. They are unlocked with an extreme psychological state and are considered a defence mechanism within the weapons.
At the point when a blast of feelings equal to the obliteration of one's heart is conjured, a power coming from the Curse Series is unlocked. The Curse Series is in actuality founded on the seven deadly sins: Gluttony, Lust, Greed, Wrath, Sloth, Envy, and Pride.
While these weapons hold great power, they also degenerate the personality of their user. For example, whenever Naofumi utilized the Wrath Shield he was overwhelmed by unadulterated disdain and apathy for others. On the rare chance that the cursed is overwhelmed by positive virtues within the user, the Bless Series is unlocked.
Naofumi believes that the curse series is an intentional defence mechanism within the Legendary and Vassal Weapons to protect the wielder whenever they suffer from an extreme psychological issue to prevent further damage. Using these weapons result in a both a psychological and physical curse upon the user. For example, Naofumi has his ability to empathize suppressed after he unlocked the Wrath Series and his stats, except for defense, were dropped by 30% after using his cursed abilities. The physical curse will heal over time and can be aided by using hot springs but the psychological effects are much harder to resolve. In Naofumi's case, he was only completely free of the curse after he unlocked the corresponding Bless Series shield which suppressed the Curse Series.
- Naofumi Iwatani unlocks the Wrath Series because of the barbarous treatment he encountered right off the bat in the arrangement because of the extreme discrimination from King Aultcray and Princess Malty. It first arose when he was vanquished by an unfair duel Motoyasu and he thought he was going to lose the only person he could trust - Raphtalia. While Naofumi has demonstrated expanding levels of command over his outrage and this Revile Arrangement due to Raphtalia, Filo, and Melty, it makes him experience overpowering degrees of outrage and contempt coordinated at his foes, which in his perspective includes the whole world. The symptom for this shield has all the earmarks of being the user losing the capacity to adore. The downside of using abilities from the Wrath Series include losing all of Naofumi's SP, losing a significant amount of blood, or being cursed with a 30% reduction in all stats except defence - depending on the ability. Finally, with Atla's help in her death in the battle with the Phoenix, Naofumi defeated his fierceness and unlocked the Blessed Series' Shield of Compassion. This shield suppresses the Shield of Wrath and allows Naofumi to empathize with others for the first time since unlocking the curse series.
- Ren Amaki unlocks the Greed Series and Gluttony Series in the wake of being deceived by Malty and having the majority of his gear and effects were taken. This happened just as he was dealing with the passing of his companions during the Spirit Tortoise assault, which he refused to take responsibility for and accuses it was due to their weakness. These two curse series were unlocked as an extension of Ren's extreme desire to get stronger. Using the Greed Series makes him more violent and increasingly risky, assaulting others to take their hardware, yet utilizing the Gluttony series makes him murderous and makes him have a go at murdering others to gain EXP and become "superior". The downsides to these swords are that he can't gather EXP nor would he be able to hold anything worth cash in the wake of utilizing the Curse Series arms Guillotine and Strong Decline. Ren stopped using his curse series weapon after he was defeated by Eclair during one of his rampages. Utilizing these swords fortunately did not have a permanent effect since he has regained his cool, albeit more humble, personality in the wake of being discharged from them.
- Motoyasu Kitamura unlocks the Lust Series and Envy Series after Malty, Elena, and the rest of his female companions sell him out to save themselves in wake of the Spirit Tortoise catastrophe he initiated. When he later realizes tries to face their betrayal and see through his self-delusions, Motoyasu suffers a complete mental break down and a deep depression. He remained in this pitiful state until Filo solaces him which inadvertently turning all of his desire towards her. While he doesn't generally have any issues in the wake of utilizing the curse series, he considers women to be literal pigs and can't comprehend their words. He only sees women in their true form if he realizes they are close friends to Filo. This is suspected to be the only repercussion to using the spears but could also be the condition needed to unlock the series. Wielding the curse series magnified Motoyasu's obsession for Filo and jealousy for Naofumi. Motoyasu is later convinced to stop his cursed rampageby Naofumi through Filo and he then joins Naofumi's village. However, since there are no serious repercussions for using his curse series, Motoyasu still uses them.
- Itsuki Kawasumi unlocks the Pride Series after being instigated by Mald, Malty, and their progressive group. He also possibly unlocked an eighth curse series, either an overzealous justice or fanaticism, during his fight with Rishia. The cursed bow gives him the ability to brainwash anyone who is hit by one of his arrows. However, in exchange for this power and a stat boost, Itsuki becomes obsessed on acting out his sense of justice. After using the cursed bow, the repercussions results in Itsuki becoming passionless and suggestible. He was willing to do anything asked of him - including taking his own life. Itsuki was later convinced to stop using the curse series after fighting Rishia and finding the note by Malty about leaving him and the massive financial debt they gave him.
- Kizuna Kazeyama unlocks the Sloth Series at some point during before being imprisoned in the Infinite Labyrinth as a way to fight against people and bypass her restrictions as the Hunter Hero. Nevertheless, it seems that at difference of the heroes of Raphtalia's World, her sloth wasn't intense and she was never takeover by the sin, still she has to pay for using it with a decrease of levels and enhancing methods, becoming weaker in short term. After the death of the other three heroes, she and her group attend a world meeting which turned out to be a trap by the Vanguards if the Waves and reincarnated individuals. While covering the escape of L'Arc, who had his weapon stolen, and the others she activated her Sloth Rod, but the enemies still captured her and attached a item that empowered the powers of the curse and make impossible change of weapon. After being rescue by Naofumi and her allies and have the item destroyed, she still was found in a state of lethargy since sloth become stronger for simple do nothing. By that time, the curse had already taken over Kizuna and started to expand as a miasma around her body affecting others. Near the end, Kizuna founds even the effort to breath annoying and tried to stop. Nevertheless, Naofumi was able to help her overcome her sloth through her passion for fishing.
- Glass: Glass was about to use a curse series weapon against one of the vanguard of the waves which had stolen L'Arc's Vassal Scythe. However, Naofumi arrived in time to prevent her from using it.
The enemies behind the wave has the technology to interfere with Vassal and Legendary weapons. With their accessories, they are able to suppress the weapons and given them to unworthy wielders. They have also found a way to use curse series weapons without the negative side effects.
- Kyo Ethnina: Kyo was able to access an unknown curse series with the Vassal Book. This gave him access to the ability Revelation which had impressive attack and some minor healing abilities.
- Takt Alsaholn Faubrey: Takt was able to use the cursed skill, Wahnsinn Claw, with the Vassal Claw. According to the Melromarc Royal healers, the curse applied with this attack is almost as bad as the backlash of Naofumi's Shield of Wrath. Takt was also able to use Legendary Shield's Wrath Series skill Blood Sacrifice but the skill was weak enough that Naofumi could blow the attack away with the Vassal Staff.
- Mald: After leaving Itsuki, Mald eventually received the Vassal Axe which had been liberated from Takt. He was able to use Guillotine and a wide variety of other cursed attacks.
- Hidemasa Miyaji: Miyaji was able to use the curse series for the Vassal Musical Instrument. This allowed him to use the ability Cursed Song: Woodo-Voodoo which creates voodoo dolls out of the target's hair. This unavoidable attack damages the target where the voodoo doll is also damaged. Miyaji was eventually defeated and the Vassal Musical Instrument left him for Itsuki.
- Harpoon Reincarnator: The enemy wielder of the Vassal Harpoon was able to use a curse series weapon and the Crucifixion skill. This skill summons a cursed cross which binds the target upon it. However, this attack was destroyed before it could be used.
- Ofuda Reincarnator: The enemy wielder of the Legendary Ofuda was able to use multiple curse series skills including one which summons demonic beings and another which summons a swarm of cursed insects.
- Light Novel Volume 11 Chapter 17
- Light Novel Volume 15 Epilogue
- Light Novel Volume 1 Chapter 23
- Light Novel Volume 11 Epilogue
- Light Novel Volume 11 Chapter 10
- Light Novel Volume 15 Chapter 6
- Light Novel Volume 12 Chapter 12
- Light Novel Volume 12 Chapter 13
- Light Novel Volume 18 Chapter 1
- Light Novel Volume 17 Chapter 12
- Light Novel Volume 9 Chapter 12
- Light Novel Volume 16 Chapter 10
- Light Novel Volume 17 Chapter 10
- Light Novel Volume 19 Chapter 11