Maybe it was a gift from an old friend or a mentor. It could be a family heirloom that he just discovered, which has some special powers or significance related to his Uzumaki heritage.
It could cause some of his friends to be worried about him. They might be afraid that the power of the demon knife will change Naruto for the worse. For example, Sasuke might be especially suspicious, which could strain their relationship further.
Well, it might make his attacks more direct and lethal. With a knife, Naruto could add a new dimension to his close - combat moves. He could use it for quick slashes and stabs, which is different from his usual jutsu - based attacks.
One possible technique could be the 'Chakra - Infused Slice'. The knife master would channel their chakra into the blade, making it able to cut through even the toughest defenses like it was butter. This would require precise chakra control, which is a common theme in Naruto.
One potential character could be Sasuke. He has always been highly skilled with weapons and his Sharingan would give him an edge in mastering knife techniques. He has the determination and the combat skills to be a great knife master in a fanfiction setting.
There's also 'Butterfly Knife Bond in Naruto'. In this fanfic, Sasuke is the one who gets involved with a butterfly knife. He uses it in a very unique fighting style that blends his traditional ninja skills with the quick and flashy moves possible with the knife. It gives a fresh perspective on his character and his battles.
Kakashi is another one. With his sharingan and his experience as a ninja, he could be involved in a fanfic where he uncovers a conspiracy related to a set of cursed knives. He then has to use his wits and combat skills to deal with the situation before the knives fall into the wrong hands.
" Forged Blade: Rebirth in a Jedi Land " was a TV series about the war against Japan during the Battle of Songhu. The play told the story of the National Artillery Major Lu Haoyun leading the troops to fight against the Japanese invaders together with the New Fourth Army led by Mei Yingsu and Fang Han. The drama was first broadcasted on the Shanghai News Comprehensive Channel on July 3, 2019, and on December 18 of the same year, it was broadcasted on the Star Channel of Central TV Department 8. The plot involved the relationship between Lu Haoyun and Mei Yingsu, as well as their heroic performance in the war. The details of the plot needed to be watched to understand more.
" Rebirth of the Forged Sword " was a TV series about the Battle of Songhu. It mainly told the story of the National Artillery Major Lu Haoyun leading the troops to fight against the Japanese invaders together with the New Fourth Army led by the commies Mei Yingsu and Fang Han. The series had a total of 41 episodes, and the specific plot and ending needed to be watched in the entire series to understand.