Good Question. I had to go back and look at them because I barely remember the kids’ titles, let alone all the Trolls. I managed to find all but 3, so here are my guesses for them

Nepeta:  Rogue of Heart

• So Nepeta is a kitty scoundrel. She might have stolen the love of someone, or even “steal the heart” of the citizens of whichever moon she is on

Terezi:  Seer of Mind

• She is able to predict her opponents moves by knowing psychology.

Karkat:  Knight of Blood

• Karkat is a violent boy who kills things. So blood of his enemy, his own blood color, and blood land. Yeah, blood knight.

Tavros:  Page of Breath

• I feel like this has to do with Tavros being able to fly, but not as high as John??

Vriska: Thief of Light

• Well, this is about her pirate days. As a thief. And I guess she steals the white piece’s stuff or ring or something along those lines.

Sollux:  Mage of Doom

• He heard his entire planet dying. He also found/fixed the game that started the apocalypse in the first place. And he has magic powers

Feferi: Witch of Life

• Kissing people can bring them back to life. Plus she can talk to animals and wants to protect life. So yes, life witch.

Equius:  Heir of Void

• I guess he gets yeeted into space. Enjoy your new home

Aradia:  Maid of Time

• She was playing the field to make sure that the correct events happen for the timeline, so yeah.

John – Heir of Breath

• With his jetpack he is able to conquer the skies. A lot better than Tavros I guess

Rose – Seer of Light

• I guess she can talk to the gods, if we view Light=Gods. Maybe. Or because she is able to talk to the White Queen.

Jade – Witch of Space

• She has a trans-dimensional dog monster. And she was able to master her dream space.

Dave – knight of Time

• He also knows how to fight, and has mastered time travel