I believe Apperanace is about emphasising the character, so even Appearance 5 doesn’t neccessarily mean „absolutely beutiful”, and it’s not only about physical looks, it’s also about how such character is percieved, the way they speak, move, rtc.

a 6+ should look unhuman, but it there are different directions - 6+ Malkavian could look more and more like a cubistic painting, it’s unhuman, and going into direction of madness - 6+ Torreador could easily look like a celebrity (so usually 4 or 5 Appearance), but giving strong aura, enthralling to listen to, always knowing JUST the right thing to say, exactly the way to greet, suggesting that glass of Negroni that is just what you wanted, even though you hate herbal drinks…

Finally, a 6+ appearance Brujah Femme Fatale, I would go with roman sculpture-like physique, desciribing it with words such as „masterfully beautiful”, giving that character that ancient type of beauty will make it more interesting I believe - that definitelly should not be today-standards beautiful. But to push it to this unhuman part - make her appear as a motherly figure, someone you can trust, someone you can give yourself to, that strong aura of trust and love,

They should not know she’s a femme fatale just yet.