Finn and Jake try to find a bandit while travelling on a bridge. Finn then tries to impress Jake by performing sword tricks. He suddenly falls and drops the sword down the trench. They search the trench. With no success, they return to the Tree Fort. During the night, Finn has a dream of being a girl thief and robbing a man in the woods.
When he wakes up screaming, he runs downstairs to find Jake and tell him about his dream. Jake tells him that it was probably "just a guilt dream." He then pulls out a sword he made to look like the Finn Sword. Moments later, Science Cat and Spear Bear call on him for the daily brawl. Finn tries to fight them with the new sword but it breaks instantly. Regardless, he beats them by knocking them out with the broken remnants of the sword. After they leave it is night and Finn decides to stay up to avoid having the same guilt dream. Jake tells him that he will stay up with him but instantly falls fast asleep. Finn proceeds to play a video game on BMO. While still awake, Finn has the same dream of the girl thief and concludes that the Finn Sword is in trouble and sending him a telepathic message. He awakens Jake and they travel to the Spiky Village.
Meanwhile, Bandit Princess (the girl thief) attacks a Spiky Village Bank security guard using the Finn Sword. Finn and Jake arrive when suddenly a building explodes. Spiky people flee in terror when Bandit Princess appears holding a loot bag and the Finn Sword. While escaping, she comes face to face with the Spiky Mayor. He offers her a deal in order for her to stop stealing from them but she refuses and cuts his head off. After running away, the Finn Sword asks her why she is a thief and she explains that she was born with rabies and her parents did not care for her which lead her to do bad deeds. She then throws the Spiky Mayor's head far away. Finn Sword sends another distress signal. Sharon explains what happened to Finn and Jake. Then, Spiky Mayor's body uses body language to tell them to follow him to find his head. Upon retrieving his head, Spiky Mayor tells them to follow Bandit Princess to the Box Kingdom.
Once they arrive, she attacks Finn with his own sword. To save him, Finn's Grass Sword sprouts from the grass thorn in the palm of his hand and he accidentally stabs the crystal part of the Finn Sword and breaks it. Bandit Princess escapes and Jake carries a knocked-out Finn home. He then hangs the now broken Finn Sword above the fireplace and BMO places a sticker of Finn's face onto the crystal part of the sword. When they leave the room, it glows bright green.
- When Jake is making his ice cream burrito, he adds equal amounts of vanilla and strawberry with a small amount of chocolate. This is probably due to the fact that he is a dog and cannot have chocolate, as stated in "Slumber Party Panic." It doesn't seem to harm him because of how little he ate, and it may be made less deadly due to only being half dog (the other half being shape-shifter as seen in "Joshua and Margaret Investigations").
- The game that Finn starts playing on BMO is called Metaphor Temple and was made by Jake's daughter Charlie.
- Science Cat's chemical fog, reading "ScIENCe RuLEs," includes symbols of four chemical elements: Scandium (Sc), Cerium (Ce), Ruthenium (Ru), and Einsteinium (Es).
- The episode title, I Am a Sword, could be a possible reference to the Simon & Garfunkel song "I Am a Rock".
- Spear Bear resembles a Care Bear, because of the picture of a spear on his torso.
- The text adventure game Finn is playing on BMO resembles games made with the tool Twine.
- Bandit Princess cutting the limbs off the spiky soldier may be a reference to the Black Knight from Monty Python and the Holy Grail.
- The title card shows the inside of the Finn Sword, which is not shown until "Two Swords."
- The Finn Sword glowing green at the end of the episode may be forshadowing the creation of Fern in "Reboot."
- The Spiky People's gold is stolen again like in "Gut Grinder."
- Jake says “Waking up screaming again… breakup? Lich? me dying? you dying? other breakup? growing up? never growing up? or spiders.” Finn wakes up screaming in "The Lich," "Frost & Fire," "The Vault," "Is That You?," "Astral Plane," and "Hoots."
- Finn having nightmares about breakups is also as reference to the events of "Frost & Fire," while his nightmares about spiders might been because of the events of "Web Weirdos."
- The Box Kingdom from "Box Prince" returns.
- Science Cat has found a new partner after Sword Shark´s death which was mentioned in "Flute Spell."
- The way the rich dude holds his money bags is similar to how Finn and Jake hold their money on "Furniture & Meat."
- It is shown that Finn keeps Billy`s sword, besides the ice sword, kunais, Ice King`s shurikens from the episode "The Chamber of Frozen Blades."
- Finn mentioned he and Jake's pet chicken, Lorraine who has not been seen since "BMO Noire."
- At the end of the episode, Jake suggests to BMO that they go get some air, to which BMO responds "Okay, I like air." This may be a reference to Air from "BMO Lost."
- Although Finn Sword itself, as shown in "Is That You?" is created with Finn in a paradox caused by Prismo's "Plan B," the Finn inside the sword calls his human counterpart "Finn Number 2."
- This episode along with "Lady Rainicorn of the Crystal Dimension," "Preboot," "Reboot," "Two Swords," "Do No Harm," "Wheels," "High Strangeness," "Horse and Ball," "Jelly Beans Have Power," "Orb," and the entire Elements miniseries are the only episodes to receive below one million US viewers on its premiere night.
- This is the last episode to air on a Saturday before the schedule went back to airing episodes on Thursdays.
- During production, Bandit Princess' role was taken up by Penny, who has not been seen since season one's "City of Thieves." Penny was likely cut because her voice actress, Violet Sole Closs Farley, was unavailable.
- The Finn Sword breaks in this episode and appears to have possibly fused with a half of the Grass Sword.
This episode was censored in some countries. See Censorship of Adventure Time for more information.