This location is not accessible on disc 4
You can visit the Esthar Sorceress Memorial after leaving Esthar, but aside from a Stop Draw point, there isn't anything to find here at this point.
Once you have the Ragnarok, come back here to save Rinoa. You don't have to fight anything to do so. At this point, your party is back to being full, and Edea is no longer available.
Once you have the Ragnarok, come back here to save Rinoa. You don't have to fight anything to do so. At this point, your party is back to being full, and Edea is no longer available.