A trout priest, (or it's big brother, a salmon priest) is very much a matter of personal preference. They can be as modern as tomorrow, solid stainless with collapsing handles and adjustable weights, or something your average cro-magnon would feel right at home with. A beautiful example I've seen that had been handed down through at least 3 generations, was simply a limb from a mesquite tree that had a knot on the end. What made is special was the care and skill that the bark had been removed with, leaving the dark cambium layer mostly intact, and then vines and thorns carved into the shaft and around the head. It had been shaped by nature almost entirely, and just happened to fit the human hand like an orthopedic casting. It had dozens of layers of hand applied and burnished oil/wax and was as waterproof as if it had been solid steel. Needless to say, it was not for sale :-(
One of the more traditional styles is made from the shaft and burr of an antler, shaped as much or as little as desired. Many are drilled and weighted with lead, then finished to waterproof. Some have resin cast around or onto the burr to make a more uniform striking surface. All have some sort of lanyard attached to hook it to a belt or fishing vest. This can be as ornate or more so than the shaft itself.
The ultimate test, of course is how well it works FOR YOU at it's appointed task. Testing this seems to involve large amounts of time spent standing in cold running water cursing bitterly, and to me seems to make the crafting of one of these more trouble than it's worth. I prefer sitting back at the camp with a cold Lone Star, and waiting for those afflicted with this particular malady to return and fix dinner. YMMV