To make her look more elegant, you should elongate the legs and to make her look more menacing, tilt the head back so that she is looking down at people. I hope this sketch helps :)

wasnt too sure how to incorporate skirt but i do think pants look nice for that elegant but intimidating feel :)

Okayyyy first of all I love your OCs character design and your art!!! I feel like if you want to make her more intimidating, you can add more over exaggerated lines and shapes especially on her wings and hair. Adding more individual hair strands and sharp thorns can rly make her character pop out! Another thing you can add is more sharp lines. If you add more lines and sharpness to places Ike the hair and wings, I think it can make her look intimidating! Sorry for the rough lines but I think this can give some sort of clue. Hope this helps!