The arm is a body part of the deceased Liege Maximo. It served as part of Megatron when he and Dreadwing raided his tomb and ordered Knock Out to attach it, replacing his original arm. With his new arm, Megatron was able to wield the Forge of Solus Prime to forge and wield the Dark Star Saber to counter Optimus Prime's Star Saber. Optimus was able to cut off Megatron's new arm brutally in Darkest Hour and it was destroyed in the Omega Lock's destruction, though the Dark Star Saber somehow survived.
- Covenant of Primus reveals that the arm belongs to Liege Maximo, one of the Thirteen Primes and not Sentinel Prime as previously believed by some of the fans.
- The arm implies Liege Maximo was red, when images show him as greenish-grey. It is possible he repainted himself however.
- The arm does not have the spikes Liege Maximo did, but it is possible they were removed.