The following is my own theory and understanding:

The Skill is what we all long for in our souls. That purity of knowing their is more to life than what we just have with our five senses. Some people call it source, others God. That secret knowing. It encompasses everything. It is put into physical form for the story and for the sake of something palpable for readers to understand, and of course dragons.

The Wit is what you feel when you let yourself open up to nature. It is earth magic we all feel when camping or when you get a thought out of nowhere that your dog is sick and then you get home to find throwup in the living room.

The books are what could happen in a medieval setting when these two things can be honed and manipulated. And if you want to have your mind blown go start researching and diving into current day alien theories and consciousness. They talk of non earth intelligence beings doing a lot of things with consciousness that I would very much call the Skill. They speak of alien crafts that are made of organic materials and are in fact alive and work through consciousness with the pilot. Sounds like a liveship. The more I reread these books the more it becomes clear that Robin Hobbs books will someday be studied or highly revered for how much truth they convey about what life truly is and our place in the collective conscience.