I thought Hanzo was just a swordmaker. Pai Mei did all the training, he did it for all of the DVAS. It’s a bit off mark if you ask me, I think Hanzo just fell bad for creating such a dangerous weapon that was used to murder innocent people. Hence the line,“I no longer make instruments of death”
Then why refer to Bill as a former “student”? Hanzo trained Bill in Swordsmanship. This Hattori Hanzo is the 100th Hattori Hanzo descended from the Hanzo in the TV show Kage no Gundan, also played by Chiba. Hanzo was a real Ninja Warrior in the 16th century BTW.