I'd go with Hick here. If you want to curse someone to be hurt, that's an attack. If you want to curse someone for bad luck so you'll have an easier time punching him in the face, that's a maneuver. If you want to curse someone to be too clumsy to hit you, that's a block (or again a maneuver that you can tag on your defense roll).
Instead of a bolt of energy smashing into your target, it would be more subtle, energy weaving around your target, tightening like a noose around his neck and finally striking, when he least expects it, making him stumble and hit his skull on the concrete.
You could also do a maneuver and tag it for effect, if you want a curse to do something besides bloody murder. Though as an evocation maneuver, I would be hesitant to allow for very big effects.
As an element, it could actually be anything, though water in its entropy capacity, and spirit as a general "invisible energy" theme would work best. But I like the Codex Alera interpretation of fire as a source of primal fear, so you could curse someone with fear. Or use air and its alignment with motion and put it in reverse and put a slow curse on them. Or a speeding up curse, where their body is too fast for their reflexes to follow. Not to mention an earth-magnetic curse in a knife factory. Always in concert, of course, with an aspect to flavor how your magic works, as described in the book.
As a focused practitioner, ritual (entropomancy) would work well, of course. Or flavored evocation, if you want to go full blown practitioner, but keep in line with the curses theme.
