Izuna smiled and said, "In that case, show me your best jutsu. I shall not use any jutsu except absorption by my Rinnegan. At the end, I shall give back all the chakra I have absorbed in a similar fashion to test your Rinnegan's absorption skills. I shall ask you to do a few jutsu. If I am satisfied with them, I shall give you this sword." Izuna was in fact doing this to see exactly how strong Naruto was. He knew Naruto was ready to wield it, but he wanted to know his strength right now.
Naruto was surprised and very happy that they wouldn't Ninjutsu spar. But for his father to be satisfied, it would take a lot of strength.
Izuna said, "First Mokuton. Grow a few trees and homes in one shot and destroy all of them in one shot using Great Fireball."
Naruto was astounded. Grow a few trees and homes simultaneously. If he was going to be asked to do this kind of stuff, he might never ever succeed. He still did not want to give up and used his Mokuton and gave rise to fifty new trees and eighty basic wooden houses. He then said, "Katon: Gokakyuuno Jutsu!" and released a huge fireball which barely managed to destroy all of them.
Izuna smiled. This test would give him information. He had underestimated Naruto. Izuna said, "Susanoó and Great Wood Dragon or Wood Golem combination." Naruto first manifested a great wood dragon and then his Susanoó around it. He de-materialized it instantly. Izuna was not surprised. He had thought that Naruto could do this. He then said, "Give a perfect lightning, fire armour." Naruto obeyed and manifested a chakra armour made up of lightning and fire chakra.
Izuna wasn't surprised at all. He looks at Naruto and said, "Now one by one, do your best Daton, Suiton and Fuuton Ninjutsu, then if I am satisfied I shall give you the sword."
Naruto was extremely happy. The test was way easier than he expected from his father. He immediately did Great Wind Breakthrough, Great Water Dragon and an extremely strong Earth Wall.
Izuna clapped. He now knew Naruto's strengths better. He unsealed the sword and gave it to Naruto. He then said, "Over the next two months, whenever I am free and you are not on a mission, I shall train you properly on how to use this sword." He then unsealed another sword. This one was a little longer. Its scabbard was made up of Chakra enhanced Diamond. He said with the utmost pride, "This is my own sword, which I created myself in the third Great War. The only difference between that and mine is that wherever there is gold in that sword, there is diamond and gold instead of silver. It also has many engravings on it.
This sword is called the Kami no Kirá/ Killer of the Gods. Well, that is the name given to it anyway. I didn't name it. I shall train you with this. Eventually, I will give this sword to you as well, but first you need to master that one. From tomorrow on you shall be present in Training Ground 44 where I shall train you in kenjutsu personally. You won't be taking any important missions for some time. Be there early in the morning. Now I need to go. Bring me a change of clothes from home. And don't ever unsheathe it. The sword is a forbidden sword. There is a reason why they are called Kami no Ken and Kami no Kirá." Saying so, he handed the Kami no Ken to Naruto and teleported to the Hokage tower.
Naruto looked at the sword pride in his face. He had wanted a normal sword and he had gotten the sword of gods. He sealed of the scabbard unsheathing the sword. It looked glorious and shone even more in the midday sun. Despite Izuna's warnings, in slight excitement, he passed a little lightning chakra into the sword, as much as chakra needed for a minute D-Rank lightning jutsu. All of a sudden, the sword was filled with chakra. Almost enough to take down the entire village of Konoha, and that much from just a little chakra which a D-Rank Raiton Ninjutsu would use up. The sword had suddenly become much heavier, due to the huge amount of chakra it contained. The sword which had weighed 10g before now weighed almost 100kilotons. Naruto was barely able to lift it. Naruto was astounded. No wonder this was called the sword of gods. He absorbed the chakra again and it gave back enough to destroy an entire nation. For a second there, he felt that he was burning with chakra and he had nowhere to let it go. For a few seconds, he was brighter than the sun! Then he just discharged all the chakra in small amounts of lightning chakra through the ground like discharge of electricity. This sword of gods was unbelievable. He could not even imagine the strength of the Kami no Kirá. Soon, he would wield the Kami no Kirá himself and make a sword stronger than that for himself.
He sheathed the sword and sealed it off so that he wouldn't cause troubles for anyone. He turned around started going towards his home. Izuna had asked him for a change of clothes. He teleported out of there in an instant.