History of the star: Al Tarf, At-Tarf (1), "The glance" of the lion (because in early Arabic astronomy, the Lion, Leo, extended beyond its present perimeters). The meaning given for Al Tarf by Allen is, "the End"  i.e. of the southern foot on which it lies on the Southern Hind Foot of the Crab Cancer.

[Star Names, Their Lore and Meaning, Richard Hinchley Allen, 1889]. 

The astrological influences of the constellation: The Crab is associated with the Hebrew letter Tzaddi and the 18th Tarot Trump "The Moon". (Fixed Stars and Constellations in Astrology , Vivian E. Robson, 1923)

The astrological influences of the constellation given by Manilius:

Shining at the hinge of the year by the blazing turning-point which when recalled the Sun rounds in his course on high, the Crab occupies a joint of heaven and bends back the length of day. Of a grasping spirit and unwilling to give itself in service the Crab distributes many kinds of gain, and skill in making profits; he enables a man to carry his investment of foreign merchandise from city to city and, with an eye on steep rises in the price of corn, to risk his money upon sea-winds; to sell the world's produce to the world, to establish commercial ties between so many unknown lands, to search out under foreign skies fresh sources of gain, and from the high price of his goods to amass sudden wealth. With heaven's favour he also sells seasons of idleness at rates of interest to his liking, wishing the swift passage of time to add to the principal. His is a shrewd nature, and he is ready to fight for his profits. [Astronomica, Manilius, 1st century AD, book 4, p.235.]