Or perhaps a fragment of the Heaven-Scorning Sword.

A sharp gleam lit Li Fan's eyes.

A Soul Arbiter of heaven and earth, using its own body as a cage to imprison a broken sword radiating overwhelming baleful qi.[1]

Long Yueyou's account instantly called to mind the scene Li Fan had witnessed: Azure Wind, holding a broken sword captive. 

But where that encounter had played out over the Congyun Sea, Long Jiuyuan's opportunity for Dao Unity had come in Tianling Province. The Soul Arbiter involved was Black Marsh, not Azure Wind. And yet the central figure was strikingly the same, a broken sword seething with baleful qi.

Li Fan was almost certain that the sword above the Congyun Sea and the one in Tianling Province were both fragments of the same weapon: the Heaven-Scorning...