This is just a mini series where I take a pair of classes that are often compared to one another by the fandom or the comic itself and rambling about them. Other pairs I have in mind are Bards/Princes and Seers/Mages. Let me know if you think any other class pairing would be interesting to hear about!
So, Kanaya said in the comic that she believes Sylphs are similar to Witches, but more magical. That line is what led many people to believe that Witches and Sylphs are an active/passive class pairing, and they probably are. I'm not really going to focus on those terms here though, as right after this I'm going to write a little ramble about my thoughts on them. Here, we're just focusing on the pair as general counterparts, classes that have similar but different powers and motivations.
What they do have in common without a doubt is the ability to manipulate their aspect, this is the common description I see being made in the fandom for Witches especially. This description is quite vague, and that's because what makes witches and Sylphs what they are is the difference between how and why they do that.
My summary is that Witches manipulate their aspect in order to break it or break it's rules, while Sylphs manipulate their aspect in order to create it or heal it.
Jade, Damara, and Feferi all break their aspect in some way. Jade broke the rules of physics by shrinking down planets and manipulating matter unnaturally. After Damara "snapped", she used her powers in order to serve the will of Lord English and screw over her sessions timelines, basically doing the opposite of a time players job. Feferi, while her powers aren't elaborated on extensively, does in fact have one huge example of breaking the rules of life; she was the one who worked with the Horrorterrors to create an artificial afterlife for everyone across paradox space.
All of Homestuck's witches break apart their aspect in order to fulfill a personal goal. Other classes may be able to accomplish similar feats to a Witch of the same aspect, but for a Witch, breaking their aspect will always be intentional and important to the story they're a part of.
The Sylphs in homestuck are Kanaya and Aranea. Kanaya may have never god tiered or honed any space powers, but she was always driven to fulfill her duty as a Sylph of Space. Kanaya was always focused on creating new home for new life. It's why she was the one always in charge of the matriorb and raising the grubs on Earth C. Space is matter and physics, but it's also the concept of creation in a biblical sense, which is why space is so intertwined with maternity and why they're always given the duty of breeding the Genesis Frog.
Aranea actually did show off the powers of a Sylph. She was able to create light in some way or another, manifesting or fixing it within others just by touching them. Her goal in the story was to fix the narrative itself, and she failed her duty as a Sylph because she focused more on manifesting her own narrative importance than she did healing what was truly narratively important. Light is luck and information about the players story and universe.
If a Sylph fails in their goal to heal their aspect, it will result in them ruining it. Aranea messed up the alpha timeline when she failed her goal spectacularly, and Kanaya failed in her goal at first when breeding their genesis frog. While Karkat takes the blame for this directly, the frog is always the space players responsibility first and foremost. This is to say, they will never purposely manipulate their aspect to break it, if they do that, it means they've gravely fucked up.
Presumably, a Witch failing in their goal to break their aspect for their own advantage will result in the aspect itself being their biggest hindrance. If their goal isn't just to break it, then something about it is keeping them from accomplishing another goal.
For a Witch, their aspect in their session is something that needs to be broken in order for them to fulfill their duty. For a Sylph, their aspect is weak or fragile, and strengthening it is their duty.
Was this ramble informative? Was it just stating a bunch of obvious stuff? Hell if I know, I just like talking about it. Hope you enjoyed reading!
If you wanna read my classpect analyses they're all organized in a google doc that i posted a link to in a different topic 👍
And yes I absolutely will get back to posting more analyses soon if anyone happens to be wondering about that
If you wanna read my classpect analyses they're all organized in a google doc that i posted a link to in a different topic 👍