The Devidians are old missions now. I went through it with my daughter the other day (she's gets spooked by them) and it had been so long since I'd played them that I had forgotten almost everything.
It was my daughters tactical character and I had her get where she could just see the tip of the boss's head. He just stood there as she fired sniper shots as fast as she could into his head. He was almost dead by the time he decided to attack.
I've tried not to give away any info that would spoil the mission for you. Sorry if I did. If this is your first time through the mission, just play the mission without trying the sniper shots to the head. Her and I have been through it several times when it first came out and we just wanted to kill the boss as soon as possible.
The Excelsior Refit is the queen of the cruisers. A lot of younger whippersnappers try to dog me out for using an older and smaller design, but I can hang in a fight longer than them in their Galaxy class varients. The only other high-end cruiser that I like is the Sovereign/Assault Cruiser. If I couldn't afford the Excelsior, I'd be in the Sovereign.