Existe uma regra para calcular Atributos Secundários baseados em Atributos que possuem valor zero ou negativo. Parece razoável - embora não apareça explicitamente, até onde eu saiba - fazer o mesmo por danos ao multiplicar pelo atributo de força.
All Flesh Must Be Eaten (Revised), page 33
Some characters have Attributes of 0 or even in the negative numbers. These levels represent Attributes that are far below average. Special rules for determining Secondary Attributes are required in this case. When dealing with low Primary Attributes, treat them as being equal to 1 for determination purposes. If the Attribute is negative, then subtract it from the resulting Secondary Attribute. ... The special rule for treating 0s and negative numbers in Secondary Attributes only applies to those that involve multiplication