On the Eternal Sphere: it's very much not just a "this is the battle system" stun like Xorn's, it's a specific property of the weapon to shoot out a bunch of stars and tie up enemies in a way few other things in SO2 do. I'm never sure exactly how much to consider it but it helping tip long fights seems reasonable. No comments on the match past that of course.
On charm: Charm is an important defensive stat in-game (offensive too but the DL deliberately ignores that) and I feel like it should be factored in in some way. There are, as noted, some status attacks that don't check it (both Silence and a few staggering blows). Another option is to see charm as the defence against AOE moves, but again that's not really accurate (staggering blows are a counterexample). On the whole though, I would consider staggering blows primarily about their damage-dealing ability, while gambits are primarily about their ability to inflict rattle (their damage is even non-lethal except all but the primary target), which leads me to the conclusion that charm should be the defensive stat against moves which are primarily about status in the DL. The other option is to subject pure status moves to evasion (since NO status move in 3H ignores both evade and charm), but that goes against established precedent that FE characters normally can't use their evade against status. On the whole I'm happier with subjecting it to charm, it feels more true to in-game. If there are other ways to reconcile which moves hit charm and which hit evade I'm all ears.
Godlike
Necrosaro (Dragon Quest IV) vs Exorcist (Bravely Second: End Layer): I imagine his double physical KOs, yeah.
Brahms (Valkyrie Profile) vs Persephone (Wild ARMs 5): VP1 Brahms is one of those weird artifacts that scans as patently unrankable now, VP2 Brahms is... good but isn't going to win many Godlike matches, and certainly not this one.
Heavy
Roxis Rosenkrantz (Mana Khemia: Alchemists of Al-Revis) vs Kain Highwind (Final Fantasy IV: The After Years): Presumably.
Edgar Roni Figaro (Final Fantasy VI) vs Dimitri Alexandre Blaiddyd (Fire Emblem: Three Houses): While I am inclined to consider Charm in general as per above, I don't think it does anything against Noiseblaster which ignores both evasion and magic evasion, making it very much perfect accuracy unless immuned.
Middle
Lorelai (Suikoden V) vs Ursula (Final Fantasy IV: The After Years): Has thunder resistance. (Might win anyway?)
Cid Highwind (Final Fantasy VII) vs Alfyn Greengrass (Octopath Traveler): Presumably. Cid can block poison, but Alfyn's healing is good enough to handle Cid's damage, and I imagine a 4-BP Amputate can dodge the scarier limits. Certainly if he lands a defence debuff first.
Light
Chemist (Final Fantasy Tactics) vs Reimi Saionji (Star Ocean: The Last Hope): Uh. If you don't allow Berserk Reimi loses horribly. But with it, she can use it and not give Chemist much benefit... still struggles to overcome Auto-Potion and it only lasts three turns. I suspect Chemist can probably pull this off.
Norris (Chrono Cross) vs Hubert von Vestra (Fire Emblem: Three Houses): Can't even hype Banshee strats here.
Locke Cole (Final Fantasy VI) vs Harley (Final Fantasy IV: The After Years): Turn 2 paralysis gives her enough time to win, Locke can't 3-2 or 2HKO her. Kinda sad.