C507 Continuous breakthrough
The Heaven's Saber Art could be considered as a type of Martial Arts that was fairly difficult to train in, with its immense power.
Even a talented individual would need at least ten years to reach ninety percent mastery of the Hateful Sky Saber Technique. It might even take twenty or thirty years.
And a single Martial Arts Seed, even if it was a top-grade heaven rank Martial Arts
