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Antonyms that are in the dictionary are marked in green. Antonyms that are not in the dictionary are marked in red.
Dual Zanpakuto is a very rare occurrence in the Bleach series, but the reason behind this isn't related to the wielder's strengths or weaknesses.
Source: https://www.cbr.com/bleach-every-dual-zanpakuto-user-why-can-wield-explained/
It's a symbol unto itself, and it has a history that's just as rich as the wielder's own adventures.