Like out of Vedas many schools were established so from Bhairava Agamas which were monistic, schools of Kashmiri Shaivism were established. Initially there used to be many schools of Bhairava Agamas but as the time passed mainly 4 schools remained.
Although these 4 different schools propagates non dualism, but they are ...
The very thought that an idea/philosophy, concept or some Shastras can remove darkness is wrong.
None of the these create the darkness (Avidya or ignorance). So,they are not capable of removing it either.
If you think study of Shastras etc can dispel the darkness then you are mistaken.
Na VedAh KArnam MukterdarsanAni Na Karanam | Tathaiva sarva ...
Yes mentioned. In ShAkta Tantras Trika refers to the Triad - JyAna (knowledge) Shakti, IcchA (will) Shakti and KriyA (action) Shakti.
But at the same time, it also refers to other Triads like the Tri Tatvas- Shiva, VidyA and Atma and etc.
Here is a reference to Trika in the KulArnava Tantram:
Trika pujAntu yah kuryAd icchAjyAnakriyAtmikAm | Agamoktena ...
Who is a Guru?
Upa=near; nayana=to take or lead (a child). Near whom or what is (the child) taken? Near the guru. That is what upanayana means.
Who is a guru?
One who has mastered the Vedas.
There is one guru during the brahmacaryāśrama (student-bachelorhood) and another during the last āśrama of sannyāsa.
The first guru is learned in ...
The main exegetical works of Kashmir Shavism (Trika Shavism) are those of Abhinavagupta such as the Tantraloka amongst others, and this drew heavily on the Kali-based Krama subcategory of the Kulamarga. Hence it isn't a sub-school, more of an influence.
The influence is easy enough to discern once its understood that the important Krama texts, Kalikrama, ...