Because of their unique tier divisions, flying swords almost never have the chance to be upgraded.
Even when a Nascent Soul Perfection Cultivator broke through to Divinity Transformation and their personal realm evolved into a Grotto Heaven, the resulting descent of Heaven and Earth's Great Power might cause their Lifebound Flying Sword to undergo a qualitative change.
However, this would only guarantee a Tier Three Flying Sword's advancement to Tier Four. The chance of a Tier Four Flying Sword ascending to Tier Five was still minuscule.
Only when all conditions were perfect—the right time, place, and circumstances—and only if the flying sword's quality and its master's strength were exceptional, was there a sliver of a chance for it to upgrade.
This was why Xiang Ji, upon seeing a glimmer of hope for refining a Tier Five Killing Demon Sword, had decisively sacrificed his own body to the blade, turning himself into fuel for the breakthrough to Tier Five.
