The Mystery of Cable's Psimitar
The Psimitar in X-Men was one weapon Cable was able to use when he was stranded in the future. Years later when he became back older than his parents, he found a Psimitar spear on a Greek Isles to harness the rest of his powers when all telepathic abilities around the world were blocked. This was during his battle with the Dark Sisterhood. Considering Cable's T-O Virus, he would definitely need this weapon. The modified version had it only respond to his Psionic imprint refusing other telepathic users.
How does the Psimitar work? It's made from an unknown metal which can reinforce and focus the abilities of psionic mutants like Cable. Also, it can be used to scramble minds and shatter nervous systems aside from being a spear. He was also able to shatter Apocalypse' consciousness form which temporarily defeated the villain. Ironically, Cable would later revive the same mutant he sought to kill after M-Day.