Pretty much what I said. But Miquella especially is meant to be a foil to The Player specifically I believe.
The Tarnished is a force of focus, determination, and sheer will. We, as the Tarnished, die over and over. We experience major setbacks. Sometimes we die twice and lose many thousands of runes, some even lose millions.
And yet we do not let it dissuade us. We may take a break. But we return, and keep going at it again and again until we succeed. We retry bosses over and over until we succeed. We try new things. But our goals remain the same. We persevere in our goals.
Where as Miquella.... is a quitter. He never sticks toward a goal. When he meets obstacles or failure, he abandons the goal in favor of something new.
When the Golden Order didn't cure his sister, he abandoned it.
When the eclipse took too long, he abandoned the people at Castle Sol and Godwyn.
When his needle failed to cure her sister fully, he abandoned her sister.
When his love got in the way, he abandoned his love.
He takes the easy way out. He never perseveres. And he is able to because of how powerful he is. And his gifts especially allow him to easily get what he wants. Where as we, as regular mortal Tarnished, have to do things the hard way.
His gift of Charm allows him to easily persuade any opponent, we must battle our opponents to move forward.
His divine power allows him to best most enemies. Every enemy is a threat to us.
He has the genius to divise contraptions and plans around his obstacles. We have no choice but to brute force our way through our enemies through the means available to us.
Of course this isn't perfect. No analysis is. But the point remains
Miquella is our foil because Miquella is a god who chose the easy way and never persevered in his endeavours, while we are mere mortals who had to claw and fight and scream our way to the position where we can fight him.
Ultimately the final battle is the poetic emblem of this dichotomy. Miquella is a god with immense power and all the advantages one could hope to have. But our relentless and unyielding resolve, determination, perseverance, and for some, the REAL genuine friendships we made (whether be with Ansbach and Thollier, or even with other Tarnished) is what allows us to best this quitter.