There's a huge section on the winged globe and the caduceus in Eugene Goblet d'Alviella's _Symbols: Their Migration and Universality_ (1894).
Goblet d'Alviella notes how often the winged globe and sacred tree are found together - often fusing into a single image. One very intriguing Phoenician image (fig. 115) shows a winged globe topping a tree with curved leaves (resembling the curves of snakes) along each side, and flanked by two acolytes: an erect ram (left) and a sphinx (right). It often presides at scenes of adoration and sacrifice.
He says that the basic elements of the Winged Globe (as originating in Egypt where it represented the sun in the valley of the Nile) include: the disk (globe), the sparrow-hawk (wings), the goat (ram's horns along top edge of wings), and the uraeus (twin serpents that hang from the globe). He also notes similarities to the flying scarab.
The Greeks sometimes transformed the globe into a winged spindle (see Chariot where the two items are separate but adjacent). Other countries (Persia, Assyria, etc.) put a god form inside the circle - often with a bow and arrow. In other words, its basic referent seems to be that of a solar deity (and the lion is generally a solar animal - Leo).
Regarding the Mithraic lion - from the Catholic Encyclopedia:
"The first principle or highest God was according to Mithraism "Infinite Time"; this was called Aion or . . . Zervan, an ancient Iranian conception, which survived the sharp dualism of Zoroaster; for Zervan was father of both Ormuzd and Ahriman and connected the two opposites in a higher unity.... This personified Time, ineffable, sexless, passionless, was represented by a human monster, with the head of a lion and a serpent coiled about his body. He carried a sceptre and lightning as sovereign god and held in each hand a key as master of the heavens. He had two pair of wings to symbolize the swiftness of time. His body was covered with zodiacal signs and the emblems of the seasons (i.e. Chaldean astrology combined with Zervanism). This first principle begat Heaven and Earth, which in turn begat their son and equal, Ocean."
Elizabeth Goldsmith, in _Ancient Pagan Symbols_ describes the Mithraic Lion as "Boundless Time": "The body is entwined six times by a serpent, and four wings having the symbols of the four seasons spring from the back. A thunderbolt is engraved on the breast. In the left hand is a key and in the right a key and sceptre or long rod the emblem of authority. At the foot of the statue are the hammer and tongs of Vulcan, the cock,the sacred cone and the wand of Mercury typifying that the power of all the gods is embodied in the Mithraic Saturn." p. 196.
According to Goldsmith, the snakes rising on the caduceus symbolise the Life impulse and the union of two creative forces. She reduces it to Pole and Circle: "the dominant, forceful upright was looked upon as Creator, and the circle was the "regulator or bridle of time and motion."
And from
http://www.corelight.org/lions/mythology.html :
"When the Prophet Daniel saw a winged lion emerge from the sea, he saw the symbolic representation of a [new era] in which Divine Truth … sets out to conquer new spiritual territory … The "lion" denotes the fearlessness of one who is imbued with Divine Truth …"
As we can see this is a truly rich symbol with lots of potential. It seems to me to come back to the creative life force, embodied in dual aspects that are attracted and come together timelessly, and surmount all else when the physical/instinctual is raised to divinity, although not yet to unity. Personally, I like to think of this card as, potentially, "the healing power of love."
Mary