Usually the prefix "a" means "not" or "without", for example: atheist, anarchy. But, in "amaze" it's not the case, since the word maze means "confusing" or "labyrinth" and "amaze" means "surprise". Is there another meaning to the prefix "a"? Or, is it not a prefix in this word?
The Online Etymology Dictionary reports the following:
early 13c., amasian "stupefy, make crazy," from a-, probably used here as an intensive prefix, + -masian, related to maze (q.v.). Sense of "overwhelm with wonder" is from 1580s.
So the a- is a prefix here, but it intensifies instead of negating. Wiktionary lists the several uses of a- and notes the Greek-based meaning you cite as the only one that remains productive today.
I'm surprise that Wiktionary does not have a sense of "to the" which I have understood to be another use of a-.
And I think it's productive, as well, as I use it to make new words, though admittedly ones that sound archaic.
How about ...
a-swimming we will go...?
Usually hyphenated, this would be my understanding of the use in amaze: "to the maze" = "to confuse my mind (with the sheer wonder of it!)"
Is there no reference that agrees with this?