To be fair, the leech power wouldn't be too bad for interrogation or something. It's just complete garbage in direct combat.
The real sad part is that he's a manipulator, so he doesn't summon the leeches, and he has to keep them on his person, and he had to alter his anatomy to accommodate them. He always has the leeches in a special leech pouch in his body, he vomits them out with a second esophagus, and he's probably constantly using manipulation to stop the leeches from devouring him from the inside out.
I'd rather get killed by a crazy clown than be that guy.