Sacrosanct
Legend
The only other piece of trivia I can add is that Vecna is an anagram of Vance, one of Gary's favorite authors, Jack Vance.As @teitan notes, the Hand and Eye of Vecna predate 1E itself; they were published in 1976, in the "Eldritch Wizardry" supplement to OD&D. They are described as the "sole remains" of an ancient lich. Very little detail is given beyond that.
So having the players know about Vecna is not a mistake. As far as I know, Vecna himself was never given stats until 2E, but that just means the DM whipped up some homebrew stats.
I do wonder where the Vecna mini came from, though.
As for how the session compared to our gaming sessions from the early 80s, the DM was much more theatrical than any DM we ever had. Oh, and with the exception of one Hispanic male, everyone else was white males in all of my gaming groups no matter where I lived until I joined the army in the early 90s.