I spent about a year training with Luffy and Rayleigh. During that time I honed my skills at using Armament and Observation Haki. However, I discovered that I didn't have the ability to use Conquerors Haki. According to Rayleigh, it's impossible to learn to use Conquerors Haki, it's just something that you're either born with or not.
I always saw it as strength plus ambition equals Conquerors Haki. That's probably not a perfect example but I think it's at least close. I never had any sort of grand ambitions, I was at the final island but I didn't have any interest in taking the One Piece or becoming the King of the Pirates. I was only there because I wanted to go on a fun adventure with my friends. Basically, I wasn't the type of guy that would have Conquerors Haki.
Knowing that I couldn't use Conquerors Haki gave the new guy a solid sense of confidence. It was the one thing that had him the most worried, but if I couldn't use it he had nothing to fear. That's what he thought at least.
We then went on to exchange attacks, though all of my attacks were blocked by his infinity and I was able to dodge all of his attacks.
"I'll go ahead and let you know, this is the weapon that will decide the outcome of this fight." I said as I drew Samehada.
"Ha! You really must be joking now. You don't really expect me to believe that you'll be able to beat me with a mid level weapon like that, do you?" The new guy asked.
"You'll figure it out sooner or later. Or maybe you won't, after all you don't seem that bright."
He then furiously began another attack and we began to exchange blows. Though again all of my attacks were blocked by his infinity while I was able to dodge most of his attacks. That being said I wasn't able to dodge them all. My left arm had been hit by his Amaterasu and was now getting melted by the flames. Undeterred, I launched another barrage of powerful attacks.
"Three Beast Sword Style: March of 1000 Ogres!!!!"
I launched the same attack repeatedly and powerful slashes tore apart the landscape. Though they obviously couldn't get through his infinity, but eventually he dodged one of the slashes.
"Ha! Finally, this is the moment that I've been waiting for!" I said excitedly.
"Three Beast Sword Style Ultimate Technique: Three Kings Synchronicity! World Eater!!!!!!!!!"
The slash of my ultimate technique flew towards him in the shape of a giant snake's jaws. He was caught by the jaws and was dragged across the other side of the island. When all was said and done, he was lying in a crater with a massive gash in his chest and was unable to move.
"H-How were you able to hit me?" He asked weakly.
"It's your own ability, you should know better than me." I said. "There's no cursed energy in this world, that means that your ability works of your own stamina. The system gave you such massive reserves of stamina that you probably didn't realize that you could run out. But my Samehada gradually chipped away at your stamina until it was completely depleted. Once that was the case I knew that you were vulnerable, that's when I launched my strongest attack to make sure that I would finish the fight in one strike."
"But how did you notice that my infinity had dropped?"
"Because you dodged one of my attacks for the first time. The only reason you would do that is because your infinity wasn't working."
"All this time it seemed like you knew that you were going to win. What made you so confident? Were my abilities not strong enough?"
"In terms of abilities, just one of your abilities are better than all of my abilities combined."
"Then, why did I lose?"
"It's because of your lack of experience, you have no idea how your powers actually work. Compared to me who's been training and fighting for over 20 years now an amateur like you never stood a chance." I said.
"So, if I trained like you did, would I have won?" The new guy asked as his body started to glow, seemingly signifying that he was about to leave this world.
I just looked up and with a grin said, "Nah, I'd still win."
This gave him a smile as well as he disappeared. With that final battle completed, me and my crew had finally achieved our goal of making it all the way to the final island. We were only the second group of people to accomplish the feat of traveling all the way around the One Piece world. The question now was, what do we do next?