Kubikiribōchō's (the great Beheader/Executioner) sword ability is neat.
It absorbs the iron from blood to repair itself. It was mentioned by Lord Suigetsu.
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While there is iron (bound to hemoglobin) in blood, I doubt it'd be enough to fully repair a sword of that size.
(It's an incentive to keep killing though.

)
Still, really creative. 10/10