User blog comment:SoulReaperBleach1/IZURU KIRA T.T/@comment-2211792-20130729042030/@comment-5551986-20130730232556

The word fallen, as implied, is a verb. I doesn't mean one dies in battle, even as likely as it is. It simply means that they collapsed due to exhaustion/blood loss or just got plain beat. If they use strong words like fall, they would also use the word dead, to describe that which is.. dead?

As for the Reiatsu, for the entire series I see Reiatsu as a pulse, the more alive and strong the person is (to an extent) the stronger the Reiatsu (pulse) as they approach death, it fades and becomes a slower pulse and harder to sense, giving the effect they are indeed dead. As seen previously with Sado during the Ryoka invasion, Ichigo briefly thought he died. And Haschwalth thought Byakuya died. Quite the contrary. In my opinion, no one is truly dead in Bleach until a funeral is held, or they are reduced to nothingness, much like Yamamoto. The people in the world of Bleach are persistent until the end.