It's a very flawed ability, I can see it.
I mean, yes, if he could talk bullshit to his opponent, enough to make them believe, then that might works. Or simply trick them is good enough. But, then again, he has no hope when facing the people who knew his ability beforehand. He also won't be able to put up things if his opponent simply thought him as a small fry. And, last but not the least, he couldn't win against machinery whatsoever.