User blog comment:Sosuke Aizen008/Can Yhwach use Yamamoto's bankai(Zanka no tachi) again?/@comment-44061-20131001133600

Yhwach did not use Yamamoto's bankai, he simply threatened to use it against him. He used his quincy abilities to kill him. Actual reading of the manga confirms that and no way showcases the use of Yamamoto's powers being used against him. Also for whatever reason the bankai is usable after the death of its wielder, Chojiro's bankai was used by Driscoll against Yama a few days after his death and funeral.