Wasn't even close to his prime. If you read the manga you would know he got weaker because he gave up on what he truly believed in. Plus Mifune gained knowledge and a sharper "blade" while living. When they were younger and both were in prime hanzou negged him by playing a swordsman game and didn't use ninjutsu at all.
Without any of those powers listed, the person scaled to the highest tier would have to be Gai. With 7th Gate he's already on the tier of many of the competitors for the strongest. With the 8th Gate, he's far and above the strongest. No competition.