Only problem being, you are aware of your enemy, so you know to block their attack. That your enemy fired on you means that they know you're there. Unless he somehow lacks the power of the knowledge, he's going to be able to block your one-shot-kill too...
I'm pretty sure the Julian and the others on the Death Evan knew from the beginning that they would be perused, since they kidnapped the queen and all that, though it might be they didn't expect them to come so fast or what not.
I think Sir Bryce and Lucian banking on the fact that the greys don't have any High level mages on board the ship to generate a shield.. or maybe they hope that Voltar is fast enough firing the Cannon so that the greys don't have time to set up their own shield.
Though... that makes me wonder now.. how is julian and the others on board going to react to them coming on Voltar's ship and all that, and with such a small party of 'heroes' to save the queen? Did they expect the royal guard to come after them with more ships? IS there someone back home in Carrreyn organizing a much larger force to peruse the Queen? *hopes later strips address this hehehe*