When Venerable Trey Walinski advanced to expert pilot, he did not live long enough to complete the Annihilator Sword Style.
Oh sure, the basics were all there. Its repertoire even incorporated a couple of empowered techniques.
Yet after Ketis fought against numerous disciples of other sword schools, she recognized that the Annihilator Sword Style possessed too many gaps.
If Venerable Trey didn't die when he was at the prime of his life, he would have been able to flesh out his sword style.
As it was, he died before he could work out the defensive and movement techniques of his sword style.
This caused the Annihilator Sword Style to possess a purely offensive character. As long as Ketis was on the attack, then she could take full advantage of the power of annihilation to demolish the opposition.