Speaking of Jusis, the way he grows combat-wise from CS1 to Reverie is something to behold.
Wish I could say the same for Laura, who's much stronger in the earlier games.
Laura shines in the first two CS games because of the smaller roster of characters. In Trails, characters are either 1. specialized for using craft damage, or if they're not then 2. you turn them into casters. In the first two CS games, the the four characters who naturally deal high craft damage are Rean, Laura, and Gaius. The other characters deal middling craft damage and can be built to deal more, but they're having to compete with Rean/Laura/Gaius who can already do much more, so you're incentivized to instead build those characters for their utility or for casting.
From CS3 onward, you have a bigger roster. Laura isn't just competing with Rean and Gaius for raw crafts damage, but also Ash, Duvalie, Estelle (her single-target S-craft with very high break damage), not to mention Reverie specific characters. And then in Reverie, everyone's S-craft gets upgraded to 4S and everyone gets an accessory that gives them +10 CP every turn, so it doesn't matter which character you bring since they're all doing at least 4S damage S-craft damage every 10 turns or less, so utility becomes more important (ie, Crow's range for evasion tanking, Rean being able to upgrade his S-craft damage to 5S+, Machias/Kurt/Lloyd/Sara for turn manipulation, etc).
As for Jusis' strength, he's not that strong in CS1 or CS3. Arts spamming is okay but not insane. It's in CS2, CS4, and Reverie when you gain access to incredible damage multipliers with Lost Arts and magic master quartz that he is able to one or two shot bosses on the hardest difficulty with his first art. Any other character can be built to do that, but Jusis is cooler. Also he has utility with Platinum Shield.