I'm not sure the "path of the flaming sword" antedates the Golden Dawn - perhaps it does, but even if so, doubt it will have much exegeted detail. I could be entirely incorrect there, but nothing jumps to mind (though it could simply be poor memory and/or poor past reading on my part).
There are three aspects to this time that come to mind. The first (and most obvious) is of course the Genesis account where the 'way of the Tree of Life' is guarded and kept by the angelic being who guards it with a flaming sword that turns in all ways.
The second and third ways derive from the Golden Dawn: the second is as another name for the 'Lightening FLash', basically delineating the order of emanation upon the Kircher version of the Tree of Life; and the third in some manner relates to GD derivatives that specifically calls the 'path' between Gedulah (Hesed) and Geburah (Pahad) by that name - also mentioning thereon that it indicates a creative impulse.
Given your own apparent past interest, I would perhaps suggest that this last be the most apt in the context.