Thank you for sharing this
For those who don't know, this was written by Vasugupta in the 800's CE after he had already written the
Shiva Sutras kind of as a commentary or follow up.
As a side note, I wanted to ask you
@Srivijaya and perhaps this is just me but I found it would sometimes cause misunderstandings when I would say Kashmir Shaivism so I tend to prefer the term Trika now days. Do you have any experience with this?
Are you saying that Shiva and Shakti is a particular conception of the Nature of God?
I can't speak for the original poster but as a believer in Trika I can say that I believe we are Shiva and that Shakti is the expression of Shiva in the material. Shivagama is to attain the status of Shiva.
To quote Swami Lakshman Joo, who helped revive Trika:
"God and the individual are one, to realize this is the essence of Shaivism."
In Trika this is done by way of Shakti hence the focus in this text on the femininity. The Triad Shiva, Shakti and Tantric (Anu) is a reflection of this as Anu (individual, limited self) finds way to Shiva (transcendent) through Shakti. This is also reflected in our other triad, ParaShakti, ParaParaShakti and AparaShakti.
Shiva is the transcendent above all, Shakti is that expression... so Shiva and Shakti are, as you say, conceptions of the nature of god yes, but also in this system the way by which one realizes that inherent nature.
I hope that explains what Shiva and Shakti is meant by here.
Regarding the concept of the divine in Kashmiri Shaivism, there's more information here:
Kashmir Shaivism - Wikipedia
I also find the Wikipedia article to be kind of inadequate. There was some edit wars over a year ago and a lot of good information is now not on the current page. That said, it's at least a start.