It's a hyphen, not a dash, so its function is not to mark a pause.
At first glance the word "light" might be taken to mean "intellectually or spiritually less than profound", in the sense that one might write of "Shakespeare-light" or "light entertainment". That is the usual meaning of appending "-light" to a word. But here I think the poet is calling up an image of hallucinated tragedy _illuminated by the experience of reading and taking in works by William Blake_ , or in a material world that one sees illuminated in a way that is comparable to how Blake saw it. So to summarise, the idea is of seeing in the light that is given by Blake's work and of viewing the world lit the way Blake saw it lit.
By the way there is a literary magazine called "Blakelight".