They could definitely do something to differentiate between skills. Ninja skill icons had to be redesigned a few months after they launched, because they were all the same color. And while most classes get a mixture of colors, most of the skills in the game are either a picture of a little man, or a shape resembling the class weapon. At least classes like warrior and monk have icons of little men facing different directions, but my astrologian toolbar is just a mess of blue and purple balls.