to be honest and this is far from purists who like butter smooth edges. i like my blade to have a bur on the edge, so it deals with snapper scales with ease.
i use Eze Lap, best value diamond steels imo.
I have a 600 grit which is as fine as I will go, takes a brr off. Get at least the 10", the 5" is fine for the boat. But if you are sharpening at speed its a bit short. Learn what angle you need and a tip, you can start by learning the distance from the blade to the stone/steel with your thumb, muscle memory almost.
http://eze-lap.com/products/oval-diamond-sharpeners/But usually I will stop at 250 grit which leaves the blade feeling a little like a very sharp saw, it will slice through paper still with ease. I also have the one with the groove for fish hooks.
http://eze-lap.com/products/diamond-stones/pocket-stones/I just to be into stropping and Japanese wet stones and hey if I had expensive knives like a $500 chefs knife Id still go super fine. But I find sharp but with a rough edge great for fish skin. Just my 2c.
I use nothing but Victory knives, keeping the money in NZ is the only way our economy will survive the housing bubble when it bursts. Plus I like them a lot. Perfect amount of carbon and steel to make easy to sharpen but strong enough to hold the edge for a decent period of time.