I think SJMaas is going to create the Valkyrie Trio Rank dynamic to mirror the Bat Boys.
Emerie (Cassian) - General
The person most connected to Illyria; a warrior zone. She has most hands on experience of the war and its effect on soldiers. Nesta and Gwyn are too emotional.
As depicted she is practical and efficient and knows how to take hard decisions (knowing she had to leave Nesta to hold the line at Ramiel for minimum casualties)
Doesn't give up in hard times (her life in Illyria and her difficulty training due to clipped wings)
Knows how to establish authority (keeping ownership of her own shop)
Good at confrontations and is able to encourage and motivate others, good team player (everytime either valkyrie lays down a piece of truth in front of each other, she says hers immediately to prompt the third one to speak and support the first one)
Is a warrior.
Nesta (Rhysand) - Leader
Silver tongued, knows how to manipulate other's emotions with her words. Gwyn and Emerie have not shown a silver tongue.
Charming and strategic.
Presents a front in front of others and can hold it as needed.
Self-sacrificing and magical prowess (owns multiple powerful objects; her made weapons and silver flame and being made herself)
Were the multiple references of being a Queen not enough?
Is a warrior.
Gwyn (Azriel) - Spymaster
Is smart and strategic and has the determination to achieve her goal that a self-operating job like a spy needs.
Is a researcher and scholar; thus indicates her thrust for knowledge in situations. Also shows ability to sift through lots of information for the important one.
The patience and observation skills she displayed in the Blood Rite are essential. (Also: I know you like to be alone)
She's perceptive of other's behaviour (when she recognised Nesta's treatment of her change when she realised Gwyn was a priestess)