Yes And fatality sounds better

Deadliness is a noun describing 'likeliness to cause death'. It is correct to use it here, but not typical of formal prose such as this. Fatality is a noun with two forms; one is a count noun which fits the sentence structure but not the meaning: a manufacturer cannot realistically be held responsible for causing a feeling of hopelessness. The count noun fits the meaning, but requires rewording: the company shall be responsible for fatalities caused by their products.