Yeah, I've always been annoyed that the Sorceress/Witches are not explained very well. I mean we get an interesting history concerning the origins of the Sorceress through the god, Hyne; yet it never goes anywhere. I sometimes wonder if Ultimecia's real goal was to become the new Hyne by compressing time, but I guess we'll never really know unless VIII somehow got a resurgence of interest again.

I feel that what most likely happens if a Sorceress dies is that they basically become a mindless zombie propelled by magic, to seek out a new host. Ultimecia didn't exactly seem all together when she gave Edea her powers.