Mister X possesses telepathic abilities whereby he is able to predict the fighting moves of any opponent he engages. These abilities allow him to "see" what his opponent will do to the point that he is already several steps ahead of them. The combination of his skills and these psionic powers was sufficient for X to defeat the Taskmaster, who is one of the finest combatants on Earth, and made it look easy.
X possesses the physical capabilities of a man that is in the peak of physical condition. His physical abilities of strength, speed, stamina, agility, dexterity, reflexes and reactions, coordination, balance, and endurance are on par with those of Captain America. Mr. X claims to be a master of every earthly form of martial arts and some alien fighting styles including Kree and Shi'ar. Mr. X is also highly proficient with a variety of weaponry including swords, knives, staffs, and firearms. He also has an uncanny tolerance for physical pain and may be a masochist.
Mister X's powers only work in one on one encounters, fighting multiple enemies doesn't allow him the time to multitask and read all their minds. He is also incapable of predicting and reading an opponent's mind if the opponent doesn't even know where they are going to strike themselves. Wolverine has managed to defeat X in combat by provoking himself into a berserker rage while they fight, thus preventing X from predicting what Wolverine will do next as Wolverine himself is unaware what he shall attempt in that state.
Mister X is a master of all known forms of both armed and unarmed combat, including numerous martial arts, boxing, and swordplay. He is also an expert assassin and escape artist, and is highly proficient with many weapons.
He is a highly conditioned athlete and possesses the normal human strength of a man of his age, height and build that engages in intensive regular exercise. While the exact amount of weight he is ultimately able to lift isn't known, it is known that he can press lift at least 310 lbs, which is twice his own body weight
Mister X keeps a trophy room stocked with various weapons including John Dillinger's Tommy Gun, an ancient African tribal spear, and a semi-automatic flamethrower once owned by Saddam Hussein.