The cases I mentioned are rare, like really freaking rare.
But RNG is RNG.. if one is unlucky enough then it's possible to run into a lot of them.
I've had a few playthroughs where I've had a lot of problems with similar cases.
Since I prefer getting my stuff from fights in this game I had to adapt to this, most of the time avoiding fights that could end up like this until I've got at least 3-4 STR on my main character and preferably a better weapon. (anything better than longsword)
This is mostly because the enemies don't need plate or the specialization to be close to immune to your damage, and in the same way you can be close to immune to their damage as well. (even a small amount of armor can reduce your damage to 1 if you don't have points in STR with a dagger equipped.. don't even mention if you're out of Energy you get a penalty to damage, which makes these even worse, as you can't even run away if you don't have Energy)
So until lv3 I usually look at fights against "humanoid" enemies as "high risk high reward" fights. (because I always play with perma-death on)
EDIT: forgot to mention but also enemies have a weird way with stats.. some enemy characters can have MORE stat points than what you would expect at their level (seen lv1 characters with up to 6 stat points), with some races this can be a pain cause if one of those is for example a race with high stat cap on STR they will hit like a truck, while a race with high STA cap will be stupidly hard to kill with some armor..