Darkness
Although Mira has had an affinity for Darkness for a while, she's never consciously thought about using it. It wasn't that she had anything against the element but that her other affinities were overwhelmingly more powerful.
She already had a versatile kit with just an ice and fire affinity. From her point of view, the darkness element brought little to the table, and she'd have to expend more effort into making it worthwhile.
However, the Guardian's words made her rethink her stance on not just the Darkness element but others as well.
'If all the elements are linked somehow, then doesn't that mean I can increase my power output exponentially if I use them in the right combination?' Mira thought, her eyes widening slightly.
Now, she understood why the Hell of Weakness was making her endure all this. One of her main weaknesses was that she wasn't even using her elements to their full potential! Hell, she wasn't even using over half of them!