It was originally linked with the ancient legend of the serpent-slaying blade from the "Records of the Grand Historian."
Big Japan and Chinese myth linking wow.
They are connecting the Kusanagi to Liu Bang's Crimson Blade that he claimed to have obtained from a Xian. I'm guessing they are going with the crimson dragon (Liu Bang) vs white dragon (Qin Shi Huang) just like how it went in Britain with these crimson vs white, and also crimson dragon (Kintoki) vs white dragon
[QUOTE=Comun;3294125]Ok, time for some script comparison.
Spoiler:
Originally Posted by OnesFleetingGlory
Sword of Heaven [...]To use this Noble Phantasm is to momentarily become a god or, in other words, to become one with the world. This is where its True Name, Sword of Heaven: Amenomurakumo-no-Tsurugi, is derived.
Cool albeit kinda generic name, but it becomes a really silly choice when the NP description drops a straight "It's called Worldblade because it unites you with the world".