Marinette runs against Chloé and Sabrina for Class President. Meanwhile, after losing an election, D'Argencourt gets akumatized into Darkblade and recruits the unwilling citizens of Paris into an army of knights.
- Advancing Wall of Doom: One is created when Darkblade plants his flag on top of city hall.
- Attack! Attack... Retreat! Retreat!: Happens as Jagged Stone comes out during the middle of the fight between Cat Noir, Darkblade, and his army. Cat Noir is seen on the offensive against Darkblade, but then fleeing from a cluster of mooks.
- Blackmail Backfire: Chloé successfully blackmails all the school students who wanted to run against her except for Marinette. Attempts ends up with Sabrina's hand being stuck in Marinette's magic box and an I Never Said It Was Poison scenario.
- Catapult to Glory: Darkblade and his army's way to get to city hall's roof after he turns cars into catapults.
- Chekhov's Gun: Marinette creates a box for her diary which automatically traps anyone (or anything, such as Tikki) inside in case someone tries to steal it. When Sabrina tries to grab the diary, it closes on her and she doesn't get it off until later on. It is also the downfall to Chloé when everyone discovers that she tried to have it stolen and exposed for Marinette to look bad.
- Comically Missing the Point: Sabrina stops looking for anything to embarrass Marinette while looking through her room to admire herself with some of her custom fashion designs and take note of what Marinette has lying around. She even dismisses how many pictures of Adrien she has. Chloé yells at her for getting off-task.
- Continuity Nod: Ivan and Mylène are still shown to be a couple, as Ivan comforts Mylène when she's scared. Kim's crush on Chloé is also referenced when Marinette suggests that she agreed to go out with him if he won't compete against her.
- Department of Redundancy Department: When Tikki learns Marinette keeps all her secrets in her diary, she asks two questions: what if someone finds out Marinette is Ladybug; and what if someone finds out Marinette is Ladybug.
- Well, averted in the English subtitles, where the second question is what if someone finds out Marinette's ladybag.
- Early-Bird Cameo: Jagged Stone is established here before taking on a larger role in later episodes.
- Election Day Episode: The main premise for Marinette vs. Chloé and Sabrina, as well as the reason Darkblade wants revenge on Mayor Bourgeois for claiming what he considers his rightful land.
- Epic Fail: D'Argencourt loses the election, acquiring the least amount of votes in Paris's history (only 3%).
- Gratuitous French: D'Argencourt's catchphrase/rallying cry in the English dub is "Par le fer" (literally "By iron", but closer to "By the blade").
- Hypocritical Humor: D'Argencourt's reaction to being accused of being stuck in the Medieval Ages.D'Argencourt: Poisonous wretch! Darest thou approach with such venomous questions. Begone now, pestilent pain in the neck!
- Imagine Spot: Marinette has one, realizing her duties as Ladybug when asked why she doesn't run for Class President by Alix.
- I Never Said It Was Poison: Chloé denies stealing Marinette's diary, currently stuck in a box around Sabrina's hand, but Marinette points out that Chloé wouldn't know it's a diary unless she stole it.
- Intrepid Reporter: Nadja Chamack as she interviews D'Argencourt. She keeps trying to find ways to interview him, only for him to turn her down. When she manages to say some insulting stuff about him, he angrily slashes apart a poster of André Bourgeois he bumped into.
- I Shall Taunt You: The Dark Blade sword tactic consists of D'Argencourt/ Darkblade dropping his guard and laying both arms spread eagle at his sides to lull the opponent into false security.
- Landslide Election: As detailed above in Epic Fail, Bourgeois's victory over D'Argencourt counts.
- The Last of These Is Not Like the Others:
- Marinette finds out that Chloé blackmailed Kim into dropping out because she'd tell everyone he's afraid of spiders, Rose to drop out because she'd kick her out of the scrapbooking club, and Alix... she didn't run, she was just annoyed with people asking her about the election, and wanted to know why Marinette just doesn't run herself.
- The students' requests for Marinette: comfy seats (Rose), music to be allowed in the library (Nino), and "whatever Juleka said" due to her being completely vague about it.
- Layman's Terms: Mayor needs someone to explain to him Darkblade's threats due to his unique way of talking.Knight: Oye, oye! Darkblade shalt speak now! Listen or be imprisoned!
Darkblade: Henceforth, my flag shalt fly over thy kingdom! Bourgeois, pathetic knave, come hither and do battle!
Mr. Bourgeois: What did he say?
Alya: Basically, he's gonna bust you up.
- Legacy Character: D'Argencourt takes up the name Darkblade, after his ancestor.
- Mythology Gag: Before breaking it, Ladybug gains Darkblade's sword. In placeholder animation, she is seen wielding a sword, but whether or not that is to be used is yet to be seen.
- The Nicknamer: While less nicknames, and more old medieval use of terms, Darkblade refers to Mayor as Bourgeois The Usurper. He also describes Jagged Stone as minstrel, and Cat Noir and Ladybug as acrobats.
- Only Known by Their Nickname: D'Argencourt's ancestor is only referred to as Darkblade.
- Paparazzi: Nadja Chamack and her camera man trespass into school grounds to squeeze an interview out of Armand, spy on him while he's having a private conversation with Adrien, and follow him around asking insulting questions when he tries to leave.
- Screw the Rules, I Have Connections!: How Chloé first gets Kim and Rose to drop out, and how she gets Jagged Stone to sign autographs for everyone to get them to vote for her.
- Signature Move: D'Argencourt/Darkblade uses the Dark Blade sword tactic a lot. Cat Noir falls for this twice, but it backfires on Darkblade once Cat is on to him.
- There Is No Kill Like Overkill: Chloé's first idea to remove Marinette's box from Sabrina's hand: chainsaw. Fortunately for Sabrina, this never happens.
- Title Drop: D'Argencourt explains to Adrien that his special fencing move is called "Dark Blade", which becomes his name later on.
- Weaksauce Weakness: Darkblade is ticklish.
- What Happened to the Mouse?: We never see what happened to D'Argencourt after he is turned back to normal, and Jagged Stone is nowhere to be seen as well. Same goes for the other characters that were turned into knights.
- What the Hell, Hero?: Tikki gives a calm one to Marinette for placing all of her secrets into a diary, thinking that someone could find out she is Ladybug, before realizing the failsafe that comes with the diary.
- Why Did It Have to Be Snakes?: Kim is revealed to be afraid of spiders, which Chloé uses to blackmail him.