"Hello friend. Seems that you found me. Good Job hahahahahaha" said the shadow as he laughed. Ace who found himself in a white space with only the shadow within it said "I found you, so now tell me how I came to this world."
And so with a grin the shadow told him "Your soul and body don't match up, meaning you died and got reincarnated. But only Gods are able of such a thing hence the Gods need you for something which is why you were reborn. And before you ask, I am but a sword spirit. I don't possess that kind of power. I don't know who brought you here but you should enjoy it while it lasts."
Having found some answers Ace asks the shadow why he called him here and it answers "I've been stuck here for the past fifty years so I decided to go out. But I need a wielder and you seem fit for the job" Ace interpreted it as such and answered "Okay. Then let's go."
The shadow then threw a sword at him and told him to pick it up. Ace confused asked why and the shadow suddenly attacked him but he was able to block the attack and it told him "I won't accept a master weaker than me. So show me what you got, King".
And so as they clashed, Ace remembered what Chris and Maria taught him. He used all he had learned and gave it his all. The shadow attacked him using black blades from the ground and Ace was wounded on his abdomen. He spit blood but the shadow was relentless and continued to attack as he took on more damage on his right leg.
The shadow shouted as he continued his attacks "What's wrong King? Are you giving up? Know that if you do, you're dead. Let me remind you that this world is dangerous. It's survival of the fittest." Realizing that fact Ace took an opening and countered as he ended up scratching the shadow's face.
Laughing the shadow said "Hahahaha that's it,your instinct. Every creature fights to survive and that is their instinct. If you fight to counter, it is because you don't want to be injured. If you fight to protect someone it is because you don't want them to be hurt and if you strike your enemy, it is to kill."
Ace due to the exhaustion as well as his physical state enters a trance and says to the shadow "Aahh I get it now. You're a wild horse. You've been calling me King ever since we started fighting meaning that I must tame you. Because the only difference between a King and his horse is instinct. I must rely on my instincts, surpass you, defeat you and make you submit to me. So bring it on, Sword Spirit." with a golden nuance in the glare of his black eyes.
At that moment, Ace disappeared and reappeared behind the shadow. His movements becoming more fluid and evading the shadow's attacks, an intense hot aura starts surrounding his body expanding further and further until all the space is filled with it. The shadow unable to land an attack is surprised by this evolution and then with a single sweep of the sword, the aura gathers on his sword forming a great energy blade and then he striked down the shadow.
The battle having ended, Ace wakes up outside the cave holding the sword which contains the shadow. It then telepathically speaks to him calling him master "You truly are strong from now on I am your sword and you my master, please give me a new name." Ace proceeds to calling him "Ryuugetsu". Having earned the sword with his own strength, he travels back home.