The Nine of Swords are entering Yesod, the fields of reflection and imagination,
and while all other Suits made themself comfortable in blessing happiness, the
Swords seem to be the outcast, called 'Cruelty'.
With the airy nature of the mind, the Swords cannot rest, they cannot stop thinking and analyzing - and in the end, cannot ignore the fact that nothing really leads anywhere, that in the end there is nothing.
(Take the technology of our century as one little example: the Wands praise the spirit of mankind, the Cups dream of all the goods that could be done, the Disks enjoy the riches it produces - the Swords analyse the effects and come to the conclusion that our planet gets destroyed.)
Therefore, it is a bit unfair to call the Nine of Swords a bad card, or criticise it for cruelty or 'over-analysing'. After all, we cannot expect the suit of the mind to tell us that we're better off with our heads in the sand, just to not see the cruel truth that is out there.
Drive: Going into the depths of a subject, with all consequences
Light: Facing up facts, realising truth
Shadow: Cruelty, pain, despair, lack of pity