Squire and Pirate both absolutely suck, and Squire moreso than Pirate.
Let's see, here you have a class with exceptionally low stats across the board. Yes you could cherry-pick some start stat that is better than in some other class, but in all cases the other stats of whichever class you compared to much more than make up for it in that other class.
You have some choices if you win the battle. Should I upgrade damage because my damage is terrible? Yes. Should I upgrade crit? Probably not because there's more important stuff to upgrade, though crit is terrible. Should I upgrade armor? It's awful, so probably. Should I upgrade health? Yes. Should I upgrade dodge? It is pretty bad, so maybe. Should I upgrade speed? Well my fighter is slow as molasses.
Then no matter what you upgrade you'll probably die a few battles in anyway, at least with Squire or Pirate. You have to get too lucky, both in terms of what enemies spawn for you to fight and in enemies missing you and you connecting hits, despite having terrible dodge percent and terrible speed. Better hope that flying fairy thing doesn't appear.