From a Mydei lover standpoint, I'm devastated to see my beloved son fighting for every second of his life.
But from the extremely pedantic lore-nerd standpoint... This lightcone is hilarious because:
It implies that nine-year-old Mydei managed to not only find clothing and armor that would fit a child just conveniently floating around in the Sea of Souls, but that he also felt like jewelry was a necessity in his life, despite having (if we approach this logically) neither any social context for jewelry wearing nor jewelry having any practical application for someone fighting daily to survive. You can't slay without slaying, I guess.
This lightcone also implies that Mydei picked an outfit at nine-years-old and never changed his fashion choices again in his entire life. Bro really said, "This outfit slaps; I'm set for good." He's literally is still wearing the exact same style as he was rocking as a homeless refugee of the abyss; I can FEEL Aglaea internally screaming.
(Yes, realistically I can guess that the artist just didn't know what else to put Mydei in and defaulted to his current outfit for reference but ssshhhhh, let me have something to laugh about right now...)