Most is adjective or adverb, comparative or superlative in the following phrase?

In the following phrase, from the 1971 film "The Devils" by Ken Russell, what is "most"? An adjective or an adverb? And in what form, comparative or superlative?

I conjure thee, most frightful beings, by this most sacred substance.

Beings refers to demons and substance refers to the blood of Christ.

First, there's a very obvious mistake, in the first part of the phrase: should be "ye", not "thee", since it refers to several things instead of one. Isn't this correct?

Second, the usage of "most". My initial interpretation was that "most" was used to mean "above everything else": the most frightful beings of all and the most sacred substance of all. But in the way that's written one can also interpret it as "something very important" but not the most important: very frightful beings.

My intention in creating the question was to elicit different opinions, views, interpretations about how "most" was used. I cannot make up my mind and wanted to confront my own interpretation with those of others to help me decide. Thank you.