Is it allowed for women to tweeze facial and other stray hairs during the three weeks?
According to most poskim, it is permitted for a woman to tweeze facial hair during the three weeks.
Emes L’yackov ftnt. 512, Halichos Shlomo 122 ftnt.9, Shevet Helevi quoted in Nitei Gavriel (Bein Hametzraim) 19-6 ftnt. 10, The three weeks pg. 32. Also see Kovetz Halachos 6-3 who is stringent regarding this.