You probably still have this ability in slot #1. Mouse over it to see exactly what it does, which will help you figure out when to use it. It's really important to NOT spam this attack - it really isn't something you're supposed to do repeatedly, since it doesn't do much damage. If you keep finding yourself in a situation where you need to use it over and over again, that's not a good thing. For example, if you're playing a Knight and you have focus points to use, you're better off using a more potent attack with your Focus points. If you're a Consular class and your Force is still high, the same thing applies.