>>715449603
May be a case-by-case study, but I think what creates this impression is how many of the unique units are strong by themselves, without much setup. Like the already discussed Berengaria, you can put her in any team in the frontline and she will be able to sustain herself and hardly feel like a detriment.
>The main thing that decides whether a class is strong is what equipment it can use and its skills
This is one reason why I was never much of a fan of Virginia as a unit. Two shields but only one special item doesn't really help her.