When Galbatorix was still a young Rider, he went on a trip into the Spine with other Riders who, like him, were overconfident in their abilities. While they traversed the mountain range, a group of Urgals ambushed them, killing Galbatorix's companions. Jarnunvösk was fatally wounded by an arrow to the heart, that had been enchanted by an Urgal shaman.
This was the catalyst that brought Galbatorix's madness upon him. Galbatorix was furious that he was "without the arts to save" the dragon and blamed the elders of the Dragon Riders for his loss. The death of Jarnunvösk enraged him, causing him to wage war upon the Riders after a new dragon was denied to him by the Dragon Rider council.
It is unknown if Jarnunvösk left her soul in her Eldunarí before her physical death and if it was in Galbatorix's possession if she had. It is most likely not the case, indicated by Galbatorix's sense of loss.
Jarnunvösk's color is unknown, but not black.
She was probably small when she died, but was large enough to ride.
Behind the scenes Edit
There were some major discrepancies regarding Jarnunvösk's gender throughout the cycle.
The dragons spared Jarnunvösk, Galbatorix’s first dragon, for it was not her fault she was killed by Urgals (...)— Arya in BrisingrIn early editions of Brisingr Jarnunvösk was mistakenly referenced as male. Later editions have corrected this and author Christopher Paolini has stated that the canon gender for Jarnunvösk is female.