How's your backhand volley? Do you use a continental grip? Is it comfortable? Does it feel natural? If it does a one handed backhand is a great weapon for you. I used to make myself hit two handers (and still do from time to time) because of my obsession with Agassi's two hander. However, I can place the ball much better and vary the spin much easier with a one hander. Not to mention, I don't have to move my feet as much (I don't know if that's a good thing or a bad thing
). Play around with it. I used to have the habit of using both in matches which can be really great unless you're under pressure and can't make a decision. For that reason, I don't reccomend using both. But give it a shot.
One thing I tell the people I work with is to give themselves plenty of distance between them and the ball on the one hander. That last step that goes into the shot should come diagonally forward with a pretty good leg lunge (not back lunge...there's a difference). It forces your body lower and through the shot. (Taking it early is recomended here) You can hit the one hander with a lot more pace by taking it early without having to work hard. Clean contact is all you need.
If you want to get fancy like Fed, try this shot...I use it from time to time and I love it. Assuming you're a righty and your opponent hits a shot crosscourt shot into your backhand side. You're aiming for the corner of the service box crosscourt. This is how Federer hits those sick angles. As you bring your racquet back and then start to uncoil, focus on the extreme left side of ball. You have to hit this shot with plenty of topspin (if you hit it flat...it's out for sure). It's a dangerous shot and one that I would practice a lot before trying it in a match but it forces you to look a the ball in a new way. There's no such thing as just forehands and backhands. There are so many different ways to strike a ball and so many different places to strike the ball. Try and open your eyes to all these different ways and try stuff that is out of this world.
Once you get it down pretty good and your opponent approaches with a crosscourt shot into your backhand, you'll feel completely confident in that sick passing shot. It won't be lucky, it will be purposeful.
Sorry for the diatribe but I get excited about this kind of stuff.