Bow and Arrow until you gain access to the Bronze Atgeir

Bow n Arrow: Use flint arrows or Bronze Arrows because Trolls are weak to pierce and both do MORE PIERCE damage than fire arrows. Don't fall for the fire arrow trap....Also aim for the head!

Bronze Atgeir: The Secondary attack (Middle Mouse Button) staggers them. Thus your attack pattern will be : Middle Mouse > Left Click > Left Click...repeat.