Board Thread:General Discussion/@comment-4906037-20140311111448/@comment-25575512-20141024121829

I think it's more likely to be "damage redirection" with the overall theme being "non-aggression". Ukitake has never been shown to attack in the manga, the most aggressive action we have seen so far is for him to re-direct starrk's cero.

What if his bankai reversed all damage dealt? If someone tries to cut or hurt ukitake, then they receive the damage instead. Ukitake is dangerous because no-one can directly harm him during bankai. (A little like barragan)

It could also explain his "illness". The first time he used the bankai on an enemy, he attacked his opponent and received the damage himself. This has never been fully healed as it was a self inflicted wound using his own reiatsu.

Think Yamamoto's arm... he used a sacrificial kido... Ywach questions why he did not get orihime to repair it, but does not mention unohana, kirinji or the 4th division! What if healing kido cannot repair wounds inflicted by your own reiatsu? Unohana explains that healing kido restores the patient's own reiatsu first, then uses it to boost the healing/regeneration. What if it works similar to kirinji's pools? By pushing out the enemy's reiatsu to remove the damage.

As a weakness, it could be that the way to damage ukitake would be for his enemy to damage himself, and have the damage reflected back to ukitake. This would explain why it is kept secret and rarely used... An almost godlike ability with a vulnerability that only someone who already knew would dare gamble their life on.

OK, massive essay there and it's built on a lot of if's but's and maybe's.. but fits so far...