User blog comment:Bloody Bankai/The Plot and Characters in Bleach ( Spoilers inside, please avoid this post if you do not read the manga as well as watch the anime )/@comment-1403595-20091024002001

Orihime is an interesting one, and I'm still waiting for her powers to be properly explained. As Minato says, there has to be a limit, because although she brought someone back from the dead before, she clearly isn't able to reheal her brother as that would require not only her power to affect a limited area, but also any area inhabited by her brother's spirit, whether hollow or rukon resident. So the time limit is probably to do with when the soul is physically seperated from the body, but really, that's only inferring from what little we've been told. Secondly her abilities are clearly limited by her reaitsu, her training with Rukia improved her healing abilities so much that she was able to heal Loly and Menoly in a very brief period of time (as has already been pointed out) and her shield has increased in strength enough to protect Yachiru from the immense explosive force of the fight between Kenpachi and Nnoitra. So in essence, her powers are limited by her raw reaitsu and the area that it can affect. But we know that already... So until Kubo reveals more, she remains something of a mystery.