Marius, the leader of the New Orleans Assassins Guild had gained from Candra the power to channel charges of bio-energy through the metal of his sword, which made it indestructible and able to slice through anything up to steel.
The father of Belladonna and Julien, Marius was the leader of the Assassins Guild until his death, after which Bella took over. After a swordfight with Gambit (in the Gambit LS) which Remy, with the help of Rogue, won, he allowed the thief to take the comatose Belladonna away in hope that Remy could heal her. He was soon afterward attacked by his son Julien, who nearly killed him. Marius finally killed Julian, declaring that he wasn't his son.
He looked for peace with the Thieves Guild and worked with Jean Luc LeBeau to arranged the marriage of their children, the childhood sweethearts, Remy and Belladonna hoping that this would end the warring. The attempt was unsuccessful and cost his son Julien's life twice. He killed his son after his insane rage against the Thieves for the Elixir of Life and rule over the Guilds.
He died when his heart gave out under mysterious circumstances. There's a strong suspicion that Candra caused Marius's death. Belladonna succeeded him. Marius died off-panel of mysterious causes. His funeral took place in the Rogue LS.
Powers and Abilities
Marius did not exhibit any supernatural abilities, but as the former Guild Leader, it's fairly safe to say he had them.