Larnneire is the key heroic figure in the overall plot of Elona, although virtually all of this plot is not in the English version of the game. She mostly attacks with her dagger, but also uses the Nerve Arrow spell. To get her Ether Dagger (and Lomias's Bow of Vinderre) at the beginning of the game, nuke the cave before entering Vernis. If you enter Vernis, they will disappear from your home, whether you have completed the tutorial or not.