YB, I also messed up the edge on a couple of fillet knives with one of those quickie sharpeners. I've now been using a diamond stone that is shaped like a putty knife. It can be used knife-on-stone or stone-on-knife.
At the sport show I bought a very compact carbide sharpener that I have not fully tested yet. It brought back to sharpness some very abused pocket knives but I'm a little afraid to use it on my fillet knife. It seems to remove alot of material fast.