Fight King's Sword is a magic sword that holds all of the Fight King's power. Its first and only appearance in the episode "Morituri Te Salutamus," where he used the sword to trap Finn and Jake in the arena, as well as the Gladiator Ghosts that he forced Finn and Jake to fight. When Finn destroyed the sword, the Fight King instantly died, and the souls of the Gladiator Ghosts were freed. Finn used the sword to "kill" Jake as his plan.
Before it got destroyed, Fight King's Sword was a double-edge sword that had two large chips on the blade. The blade was yellow with the glowing aura of the Fight King's powers. The sword contained a green jewel on the top of the handle, along with 2 similar-looking handles coming out the sides. The main handle on the bottom one was longer than the ones on the sides.
- This sword also resembles a cross, similar to the Demon Blood Sword.
- This made a cameo appearance in Issue 1 of the Adventure Time Comics.