Makiko said that The dragon is the same, but they can take two different forms: Either become the Black Dragon and strike the Earth (Abusing their god-like power to cause chaos and destruction), or become the Flying Dragon and soar through Heaven (Using their god-like power to help others and save the world). ONE dragon, but two natures depending on the choice. Dougen said that this True God would possess all of the power and he would control that person to rise back up in power. Mitsuomi said that he would defeat even that person if it messed with his plans. The only person who can gather all of that power and actually be a god at this point is Souichiro. But like most of people kept telling him: the fight with oneself is the greatest fight one would face.
The black dragon and the flying dragon, neither of them could represent being the true warrior, but the true demon and the true god respectively.
You're saying that Mitsuomi was fighting at 100% right? Shin wanted someone to take him out if he couldn't gain control of his Dragon Eyes. Trying to control his instinct of just killing Mitsuomi right then and there. Like you said, Mitsuomi was fighting at 100% against Bunshichi too, but Bunshichi obviously would've won if he was a killer. Masataka isn't a fighter by nature, but has the experience and skills to make him a very formidable martial artist, but he can never reach the level that other characters can go because he only has a purpose in fighting, like everyone else. You can't say that his purpose is the most noble cause everyone else on the team basically has the same purpose to get stronger at this point. He's fine as he is. He doesn't need some fancy title.
Shin did fight Mitsuomi at a hundred percent, and he did it with a handicap. He was the one holding back during the that fight, not Mitsuomi.