The Dark Star Saber, or Slayer of Primes as Megatron called it, was a Dark Energon version of the Star Saber created and wielded by Megatron through an arm of a Prime he took and attached it from its body and the Forge of Solus Prime. The Dark Star Saber possesses all the powers of the original blade and was stronger than it's predecessor (at least in their initial encounter) and unlike the original blade, this one doesn't require a Prime to activate its powers and it's far more sinister and malevolent.
Megatron, after securing the arm of a dead Prime from a tomb, used the Forge of Solus Prime to craft a counterpart to the Star Saber out of a huge chunk of Dark Energon. Megatron first brought the blade into action after the decoding of the next Iacon relic in Egypt, and used it to make fools out of Arcee and Smokescreen. The waves of energy it created threw Smokescreen against a pyramid. When Optimus arrived with his own Star Saber, the two engaged in battle, but the Dark Star Saber would prove to be stronger, breaking Optimus's sword.
He took the sword with him to Cybertron to find the Omega Lock. He got the opportunity to use it when the Autobots showed up, and Optimus attacked him with the reforged Star Saber. It also proved capable of destroying the Spark Extractor when Smokescreen used the device against his men. After Megatron began using the Omega Lock to cyberform Earth, Optimus charged at him with the Star Saber. Megatron managed to counter his first blow using the Dark Star Saber, only for Optimus to slice his sword arm off at the elbow. Both sword and arm were subsequently caught in the explosion when Optimus destroyed the Omega Lock.
Final Use by Megatron
At some point, the sword was found, without the Prime arm, and kept aboard the ship's vault. When Predaking went rogue, Megatron decided he would use the sword against him. Unfortunately, Predaking found him first. Using his wits, Megatron defeated him and Knock Out brought the sword moments later. Megatron then armed himself with the Dark Saber when he learned that the Autobots were invading. Megatron used the Dark Star Saber in his fight against Optimus, but briefly lost it. After Megatron killed Bumblebee he was able to regain his sword and attempted to use it to kill Optimus, only to be killed by Bumblebee (revived by the Omega Lock) with the real Star Saber. As he lay dying, Megatron dropped the Dark Star Saber, which fell down to Earth.
The Dark Star Saber returns in Transformers: Robots in Disguise
As revealed in Mighty Big Trouble, the Dark Star Saber was found at the bottom of the Earth's ocean by Clawtrap and the Scavengers. However Starscream showed up, tracking down the Minicons, and quickly reclaimed the sword. Strangely, the Dark Star Saber was starting to reject him.
In Mini-Con Madness, Starscream observed that the sword seemed to think he wasn't totally worthy of it, but continued to utilize it anyway, including threatening Bumblebee and hunting "Earth rodents" when not carrying it clamped to his back at all times aboard his ship.
In Worthy, when Starscream went into battle against the Autobots and Weaponizer Mini-Cons, the Dark Star Saber showed the ability to unleash a pulse of stunning electricity, knocking out the Seeker's opponents to the last bot. Following his defeat by Optimus Prime, the Dark Star Saber was locked away on Optimus' ship for safe transport back to Cybertron.
- Megatron (creator and 1st former holder)
- Knock Out (briefly-carried it to Megatron)
- Clawtrap (unsuccessfully)
- Starscream (user but wasn't worthy enough for full power)
- Megatron's eyes should be purple around the sword as his eyes turn purple around other sources of Dark Energon.
- Megatron was able to use it without his Prime arm. It's possible he used the Forge merely to create the sword and used the Dark Energon in his spark chamber to control it, or that the sword didn't have any requirements for its use. Starscream's later comments on the sword imply any Cybertronian can use it, but only a user of Dark Energon can access its full power.
- Despite being associated with him, Megatron only uses the Dark Star Saber for combat in 4 episodes.
- In season 3, the Dark Star Saber and Star Saber never clashed together.
- The Dark Star Saber had something of a counterpart in Transformers: Armada media, as the Mini-Con Star Saber-when wielded by Galvatron-took on a dark coloration.
Main Article: Dark Star Saber Gallery