[alexti]

I feel that human commander's HP are just fine. It seems normal that a single lightning bolt, or a hit by a giant, or even a well aimed arrow can kill them. They're pretty cheap and easily replaceable (it's good idea to have few spare commanders in your army). They're commanders because of their leadership skills, not because they're superhumans. Though they usually pretty good fighters and can often defeat 2 regular human soldiers.

And even Niefel Jarl can be wiped out in pretty much one shot. Ok, paralyze may not kill him outright, but routing work by a few soliders will finish him in that state.

I don't think it's a good idea to put too much equipment on those humans - they die quite easily. I'd usually put some cheap shield and armor so that they can survive stray arrows and, appropriate cheap magic booster when necessary. Of course, the end game is another story and you have to equip all your battlemages (armor and at least fire and cold resistance).