Also from the same page referencing non evil uses: " This semi-precious stone was carved for jewelry and decorative housewares and was hard enough to wear well. It was often used for sculpting figurines (including the magic onyx dog)." "There were "nine secrets" that could be enchanted to become an ioun stone and onyx was one of them. Physical contact with onyx helped reduce complications and pain during childbirth." "Onyx was a common stone among the drow, a gem worn by drow of average station, albeit they used only black ones."
There are positive and negative things associated with it, much like symbols and gemstones in the real world. In both the real world and in the FR there will be people who turn into raving lunatics at the sight of something they find offensive or bad, but many more will just ignore something like this because they don't know for sure why the person is wearing it.
Shadowheart's attire choices should perhaps be modified a bit so she has less of the "suspicious looking black circle thingys" but I still believe that most people would just ignore her or steer clear if they expected her to be bad rather than confront her over her choices. For our characters there should be some sort of unbiased information given about Shar when we first meet Shadowheart and more if we pass a religion check, this would help those who are unfamiliar with the lore.
