Complex sentence: Snorri's assertion that' neither fire nor iron told upon them' is reiterated time after time, and the sources frequently state that neither edged weapons nor fire affected the berserks, although they were not immune to clubs or other blunt instruments.
Split into simpler sentences: Snorri's assertion that "neither fire nor iron told upon them" is reiterated time after time. The sources frequently state that neither edged weapons nor fire affected the berserks, although they were not immune to clubs or other blunt instruments.