The Demon Blood Sword first appeared in the episode "Dad's Dungeon." It is also called The "Blood Sword," The "Demon Sword," and also "Jake's Family Sword." Joshua created it to be given to Finn, so he placed it in a dungeon so he could claim it. Apparently, Joshua and the Blood Demon, from which he took the blood from to make the sword, go "way back." But Joshua won't give the sword back, and sets the Blood Demon on fire by saying "Kee Oth Rama Pancake!" Whenever he appears. It is Finn's new primary weapon, appearing in most of the new episodes.
The demon sword is blood red, probably because it is made out of demon blood. It has a circle with a cross through it, separating the hilt and the blade. In the game Fight-O-Sphere, the sword is yellow. It is unknown if this was purposely done, or a mistake.
- The sword resembles a cross.
- From its second appearance and on, the tip of the handle is white.