Board Thread:Questions and Answers/@comment-9826910-20130618064245/@comment-11051098-20130718183608

In the case of Driscoll Berci, who stole Sasakibe's Bankai and killed him, Yamamoto said that "his (Sasakibe) Bankai was never this weak". It seems, for a 2nd option or maybe any Bankai except Zanka no Tachi, that any strong Stern Ritter can use a strong Bankai, but not use more of its power than what they're able to wield.