How Do Troll Regeneration work?

Bleeding can be halted, cuts and braises can be mended back, apparently they can grow back limbs like a starfish and they have insane endurance. Their weakness according to the wiki, is decapitation, poison and good'ol fire.

So for an average non-troll warrior with no access to fire magic (maybe a torch), are they screwed when pits against them?

I can't imagine the rangers of Quel'thalas have access to fire arrows (or maybe they had) when fighting against Amani trolls unless they went for the head and even then, the trolls can just regen back their eyes or maybe brain.