In reality, their so-called fearlessness stemmed mostly from the fact that they had nothing to lose.

At the very least, that was the case for Onean, and as for Erwin, he simply didn't want Onean to face the ice dragon on her own.

Despite his apparent lack of fear and hesitation, how could he not be fearful in the face of such an enormous ice dragon and such a ferocious storm?

The two of them adopted different approaches to warding off the oncoming storm.

Onean conjured up a fiery tornado around herself to oppose the ferocious storm, and the sparkling particles of azure light immediately clashed violently with the scorching flames. As Onean increased her magic power output, the storms of fire and wind continued to rage incessantly, and neither side was able to gain the upper hand.

As for Erwin, as soon he flew into the storm, he immediately conjured up his light shield to protect himself. The countless azure particles of light around him began to assault the outer wall of his light shield in an irregular fashion, and Erwin discovered that not only was the storm extremely fierce and powerful, the particles of azure light were also quite remarkable.

Upon closer inspection, he was shocked to discover that time inside these particles of light was completely still as well, which meant that they were essentially countless minuscule light shields. 

Could it be that the magic beasts in these mountain ranges...