Well mel use AM 3000 years ago with a conscious when his conscious (emotion) was taken he didn't want to enter that mode because it makes him more evil and revert to his evil self. Plus when mel in AM or with the AM mark he become more evil or cold hearted
It's not suppose to rival it but for escanor to hold his own remember this is his last stand like someone say madara vs guy but the dk ruler will nullify most of escanor attack....well up to nakaba sensei
So people should take into consider it probably noon and escanor is about to transform to the one. And that why he was able to block remember mael say it's almost noon
Maybe the sinner will buy time for them from Crisis power up.
Ban is gonna fight pull some slick moves then demon king laughing in amusement an then proceed to fodder ban sinner appear buy time everyone escape zeldris including and regroup elsewhere