Quote Originally Posted by paper mache
Archi, if I remember during the first encounter with grand fisher, Ichigo thought the shinigami died when he tried to save his two younger sisters, then after that Rukia explained to Ichigo, shinigami's can die and when they die that's it.

I don't remeber Rukia or anybody else in that matter go in depth of the death of a shinigami after that.
That shinigami was filler. He wasn't in the manga. The real fight of Ichigo and Grand Fisher was animated as a Jump Festa OVA loyally to the manga.