Sword bone
A mortal with no spiritual roots or background, only a mortal body that is said to have "no path to immortality".
He was thrown into the most dangerous wilderness frontier, and everyone thought he would die.
However, he used his mortal wisdom and his fearless will to forge an "immortal sword bone".
When the giant of the Immortal Sect looked down at him, an "ant", he just slashed out with his sword and said softly:
"Immortals are nothing more than that."