In the end, Hverg and Mjoll found that the Chief had allowed Giants to overrun the Shrine to Malacath. In order to remove the curse, he needed to give their leader's weapon as an offering to him. Of course Yamarz drags them with him, seeing as they're the reason why he's doing all of this.
Then he has the gall to offer Gold in exchange for killing the Giant for him. Naturally, Hverg refused heavily. Yamarz said it would only take a second.
Yep, only a second.
In the end, the two of them had to take the Giant down and retrieve the weapon on their own.