Micaiah is almost a textbook definition of a mary sue.
>fancy hair colour, different from every one else
check
>super special powers noone else has
check
>everyone thinks she's just amazing
check
>no visible faults
check
>replaces the main character in importance
check
>inflated value to the plot for no good reason
check
combine that with the fact that she's a garbage unit in the game, has to be babied in every single stage, and that the character she's upstaging is fucking IKE, and yes, micaiah is the worst lord in the series, and one of the worst characters in the franchise, if not THE worst.