
mind is always represented by horse as it is very speed.
the sword represents the asta ma sidhdhies (eight great powers)(eight great perfections) now see the kalki aspect in this angle you will get some clue.
Whenever and wherever there is a decline in religious practice, O descendant of Bharata, and a predominant rise of irreligion at that time I descend Myself. In order to deliver the pious and to annihilate the miscreants, as well as to reestablish the principles of religion, I advent Myself age after age.