Board Thread:General Discussion/@comment-4008620-20190228152351/@comment-35233810-20190308201225

I think I finally realized why he couldnt use his bankai or "fix his Reiatsu properly." first though, you guys are right i was reading too much into this and not re-reading the source material. now to what i realized. Firstly, we know that the Reiatsu is the manifestation of one's spiritual energy and, as shown in the anime and manga, one's blood is the source of it. However, it seems Isshin's Zanpakuto draw its strength from it, as show in the anime, where he drip a few ounces of his blood on the blade creating a massive spiritual attack. therefore, we now know why whenever he uses his bankai, it puts a tremendous strain on his body....it feeds on his blood. so when Aizen slashed him creating that wound, he knew if Isshin used his bankai it would have made that wound worst because of the strain place on his body. furthermore, that is the reasons why he began to fade in the battle and nearly died, even when he was using his shakai. Cause remember, the shakai and the bankai's ability are linked.