I grew up with Pound Puppies and the Legend of Big Paw and there's a female character in there bearing this name. I cannot see the name as masculine despite its history.
I'm not a religious person so initially the name was too associated with religion for me. However, it also strikes nostalgia and a strong association with Christmas due to the carol "O Come, O Come Emmanuel". I don't hear it so much now, but when I attended my Catholic primary school, it was very common. Hearing the name, I just picture children singing, wearing tinsel and Christmas cracker hats, sitting cross-legged on the floor with a glittering Christmas tree in the corner etc. It's a peaceful and kind sounding name.If I were to use it, I would use it due to my personal association and not the religious one (I realise Christmas is technically a religious holiday, but as a non-religious person, I celebrate everything but the religious part).
Shouldn't this name be listed as "feminine" in use also? Glenn Close. Sure it's a rare usage, but it's a usage nonetheless. Perhaps at least note that it's had feminine use?
Mungo Jerry, a British group from the 70s. The name was inspired from a poem called "Mungojerrie and Rumpleteazer". I am unsure where Mungojerrie comes from, but if it is a real name, Mungo could be a short version of it. I also think of Mary Mungo and Midge.
Just mentioning that this is also a word-name. Opaline means "opalescent". It also refers to types of glass what are opaque or white semi-opaque. Basically Opaline means "opal-like". [noted -ed]
This name has grown on me considerably after re-reading Harry Potter and the Deathly Hallows followed by (I'm sure) hundreds of Marauder era / pre-Azkaban fanfics. The character of Regulus Black (although we don't know much about him canonically) gives the name a strong feeling of cunning and bravery. If I were to name my child Regulus, I would do so hoping that he would grow to be very intelligent and ambitious.
I grew up with the film Cats Don't Dance and there's a female character in that movie called Sawyer. I find it hard to see this name as a primarily masculine name because I associate it so heavily with her. Though, while I find it unsurprising it's viewed as a masculine name (Tom Sawyer, Sawyer from LOST etc), I am surprised it isn't marked as a male AND female name...
I had a childhood friend with this name and the pronunciation listed is not how she and her family pronounced her name. It was less sounding like "Chinese" and more like SHAN-eese (like the English pronunciation of Rhys). Edit: Upon reflection, this may have been because she was a white British girl from a white British family while the name is listed as African-American.
I mostly know this name from Sirius Black (Harry Potter series), however I've also been introduced to a female Sirius so I now associate the name with both genders. I suppose it helps that the constellation Sirius, the star, is from that of a female dog called Laelaps.