The Wafer is more likely the Communion wafer than Klonopin[]
It says in "trivia" that The Wafer is a reference to Klonopin. I always assumed it was a reference to the communion wafer used in Christian communion. It looks exactly the same (traditionally the wafer is a whitish yellow circle with a plus sign style cross in the center - google "host wafer" to see) And also the communion wafer kind of fits in a little better with the theme of the game than Klonopin because in christianity its supposed to become the body of Christ during communion and become sacred.
I think if the reference to Klonopin is left in it the wiki it should be written with a "maybe", unless Edmund is on record talking about it. It just doesn't seem as likely.