Personally I would go with
Precognition, but with the enhanced brain power to perfectly understand all of the incoming information. Super dexterity, but as I use this power I exude black smoke. The more active the dexterity, the more smoke. Prof's ability to particalize (not sure if that's the right word) material around me.
As for my weakness, my body would start to decay if someone brought an ancient Mayan sunstone near the woman I love. But if the stone is taken away I immediately regain lost body mass.
My cheesy name would be The Final Night.
I would run my domain from behind a figurehead or just work as an assassin. My abilities may be awesome and useful, but they are not aesthetically pleasing. I would find a lesser epic, maybe an illusionist or someone who could blast lasers or energy at targets and use him. Anyone who displeased me would have the chance to challenge me to single combat, or be tortured to death.
My costume would be cargo pants (so much storage space!), a couple of solid steel knives strapped to the small of my back, leather and sci-ti (scandium-titanium alloy generally used in lacrosse sticks) medieval cuirass, a cape cut into strips (like a mistcloak), and an operational "balaclava" (like Deathstroke, only cooler).