The documentation for PROC UNIVARIATE says: "Note that confidence limits for percentiles are not computed when a WEIGHT statement is specified."
However, recall that you can use regression procedures to carry out univariate analyses. Click on the link and scroll down to the third bullet to see how to use PROC QUANTREG to estimate quantiles and include confidence intervals. The QUANTREG procedure supports a WEIGHT statement. For example:
ANOVA, or Analysis Of Variance, is used to compare the averages or means of two or more populations to better understand how they differ. Watch this tutorial for more.