The griffin is not understood by any scholar, at least, I still need to find the one who did. It is by far my favorite symbol together with its tree of life, eternal flame, vase/chalice with flame, or torch of enlightenment. Usually the griffin flanks these.
In my opinion, it is pure symbolism, a metaphor/union for the strongest being of the land, the lion and the strongest being of the sky, the eagle. It is a symbolic Hieros Gamos, Zeus eagle (or Horus) and Cybeles lions (or Sekmeth) (like the square and the circle of freemasonry or the red and blue in ancient paintings.)
Its flanking either the tree of life or the eternal flame, symbolic of life and the cosmos itself, hence seen in heraldic images and on chests of Ceasar Trajan.
This post and research by: Stijn van den Hoven – facebook.com/stijnvdhoven