Board Thread:Questions and Answers/@comment-11398218-20130629184317/@comment-5398287-20130809162732

In this case, Byakuya's Bankai is next to impossible to destroy because of how much of it there is. Sure, you might permanently break a blade petal or two, but on the whole, that's gonna do pretty much nothing because there are a bajillion more. Compare that to Tensa Zangetsu, which only has one blade, and you can see why breaking that would render the Bankai next to ineffective. Essentially, "breaking" a Bankai lowers its effectiveness based on how much you "broke". In the case of Ikkaku, one of his blade, the monk's spade iirc, was broken off at the hilt in his final clash against Edrad. Now, I'm not sure how Akon fixed it, but Mayuri states it isn't as powerful regardless, so I'm led to believe while the other two blades are fine, that one has been weakened. It should also be kept in mind that similar to Komamura's Bankai, the shihakusho of Tensa Zangetsu can be reformed after it loses material because it reflects the level of Ichigo's Reiryoku. Additionally, up until he had his Zanpakuto reforged, he still had the hyper-speed combat going for him (although that pretty much means nothing now). Anyhow, getting off topic. While I'm sure at least some blades of Byakuya's Bankai have been broken or damaged in the past, you literally wouldn't be able to tell by looking at it because one or two out of a bajillion is almost nothing.