That SH ordered Sorilea to teach Elza the weaves, so that Elza could fetch the Domination Band, if SH could then also simply order Sorilea to fetch the Domination Band; it's less complicated. Also BS's statement that "Elza was essential to Shaidar Haran in getting things done" speaks againt the diea that SH could also have used Sorilea with less problems.

I think this argument also speaks against the involvement of another female Forsaken.