"The factors to be taken into account in assessing seriousness are: It is the element of violence that is the most serious part of the offence of robbery, but it is not the only determinative factor. The relative seriousness of each offence depends on factors such as the degree of injury to the victim or the nature and duration of threats. The degree of force used is important in determining the seriousness of the offence but the degree of fear which was experienced by the victim is a relevant consideration. Use of a weapon or presence of a weapon even if not used."