Variables are implicitly weighted differently because variables with larger variances have larger effects on the clusters. See the Details section "Using PROC FASTCLUS" and the example titled "Standardization of Variables in Cluster Analysis" in the FASTCLUS documentation. To make the variables have equal effects, standardize them so that they have the same variance. To weight them differentially, standardize them so that their variances reflect the weighting that you want using PROC STDIZE.