[LDiCesare]

Death would cause more afflictions, including against a regenerating giant, but fire would hit more often.
Against Niefelheim, fire is definitely better. Against Hinnom, I'd have to test, but MaxWilson is quite right that the +4 attack can make a big difference.
However, Death bless +%affliction affects all attacks, including spells and missiles, which makes it useful if you have sacred mages.