A weapon that can manipulate time might also be considered perfect in Naruto fanfiction. Imagine being able to slow down or speed up time during a fight. It could change the outcome of battles completely. For example, it could be used to dodge attacks that are otherwise impossible to avoid or to land a series of attacks before the enemy can react.
In Naruto fanfiction, a weapon that can absorb and then redirect the opponent's jutsu could be a perfect weapon. This weapon would be especially useful against strong jutsu users. The wielder could absorb a powerful fire - style jutsu, for instance, and then redirect it back at the caster or towards other enemies.
One possible perfect weapon in Naruto fanfiction could be a sword that can cut through any chakra - based defense. It would give the wielder a huge advantage in battles against powerful ninjas.