|Owner|| Finn (currently)
|Introduced in||"Dad's Dungeon"|
The Demon Sword is the sword that Joshua formerly owned. It was for the family, and is at the end of Joshua's Dungeon for Finn and Jake to explore in the episode "Dad's Dungeon." It is made entirely out of Demon blood, as explained by Joshua in the hologram video that he made for Finn and Jake in the future to "toughen up" Finn. The sword seems to resemble a Celtic Cross, which is odd, considering it's being made out of Demon blood. It was found in the last chamber of the dungeon, and was used to defeat the Evil Monster. It was locked up with chains and stuck in a rock when Finn found it, with the key for it around a monster's wrist. Instead of defeating the monster to get the sword, Finn ripped it from the rock, breaking the chains, and subsequently used the sword to dispatch of the monster. This sword replaced the Root Sword that Finn found in "Mystery Train." Finn used this sword for the first time (not counting "Dad's Dungeon") in the episode, "Return to the Nightosphere." It seems that the design for the sword was slightly changed for that episode, the tip of the handle is white instead of red.