What is the ruling on liability for death caused by a poisoned iron weapon?

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If a person strikes another with a poisoned iron weapon and the poison reaches the soul causing death, there are two opinions regarding liability. The first opinion states that the *aqilah* (blood-relatives responsible for accidental death compensation) bears the liability because the act is not pure intentional homicide, resembling intentional error (homicide by intent that is treated as error). The second opinion states that the *aqilah* does not bear the liability because the weapon used is one that typically causes death, thus resembling a case where no retaliation (*qisas*) applies.