Zarkas

The reason the mercenaries are up in arms is because of their dead colleague. Of course, Barrakas' friend didn't kill him, but he did die while on the chase. The dead fellow's name was Zarkas. In order to calm the mercenaries down again, they'll want Barrakas' friend dead, but then all your efforts would go to waste, so I've been acting as a mediator. To mercenaries, weapons are like their own children, but when Zarkas died, his weapon disappeared as well. He was killed by Robatoms in the Death Plains. Get Zarkas' Sword from them.

This is the most important task right now. Go to Death Plain and retrieve Zarkas' Sword from the Robatoms.

This is definitely Zarkas' Sword. I may be able to persuade them with this. Wait while I talk to the mercenaries.