Valira was on Arisen Grade as she was the Awakened One. Zayne realized this from the beginning because of her unusual aura.
However, although Chaos gave Valira a chance to continue living, Chaos did not heal her completely. Her bleeding and strength were restored, but some wounds remained as well as the fact that she had no arm.
It may have seemed insane to the average citizen of this world, but more often than not Chaos acted justly, much more often than Fate, to whom all the inhabitants of the empire obeyed.
If Valira had not been injured, Zayne would not have stood a chance. He was able to take Toruf to the ground with great difficulty, who had no intentions of killing him or fighting him seriously. Valira was different, she had to do anything for victory or else she would die, no matter from Zayne's sword or because it had already almost happened.