A fillet knife that sharpens while you cut? That’s the bold promise Relentless Knives make with its Curved Fillet Knife.

In its pursuit of the elusive long-lasting edge, Relentless Knives called on titanium, carbide, crushed diamonds and nature. Using beaver teeth as a model, the company promotes blades that “sharpen as they cut.”

A “Power Strip” consisting of ultra-hard carbide and crushed diamonds is permanently bonded to one side of the titanium edge. The basic concept is that as you use the knife, the softer back side of the blade wears away, exposing more of the hard edge. The need for constant resharpening is eliminated, ergo Perpetual Edge Technology.

According to Relentless, you need not worry about your blade rusting or discoloring, even in saltwater, a dream for commercial operations or the fisherman who forgets to wipe his knife off after use. The base line is that the knife—in this case the Relentless 6-inch Fillet Fixed Blade—must cut. Let’s see if it does.

Relentless Knives Curved Fillet Knife Specs

Company: Relentless Knives
Blade length: 6”
Blade material: Grade 5 titanium
Power Strip: Carbide/crushed diamond
Blade grind: Flat
Blade flex: Medium to stiff
Handle material: True Grit glass-reinforced ABS
Weight: 6 ozs.
Overall length: 12”
Sheath: Leather w/snap strap
Country of origin: USA
MSRP: $150

Curved Fillet Knife Cutting Tests

The paper slice is a quick way to check any edge. The fillet knife sliced strips of 20-pound copy paper without pressure, and I could feel the Power Strip grab the paper. Sharp, coarse cuts, the slices were not difficult to control and the handle felt comfortable.

Single-walled cardboard was next. The first couple of slices were rough cuts, then it seemed to smooth out a bit making for faster slicing. The True Grit handle material really keeps the knife locked in your grip.

I started cutting scrap 8-ounce leather. At first the edge was still grippy while slicing, then seemed to find its groove and got smoother. The cutting action was very aggressive—I could hear every cut. Using the other end of the leather strip, I did some skiving. The slices were thin and I still heard every cut. Using a choke-up grip, control was very easy.

It was scrap-pine whittling time. The knife produced some nice curlicues. Note: use the edge close to the guard for stability. The Power Strip wanted to dig deeper into the wood, so I had to control cutting depth. It’s fun to try but watch out for your fingers!

It was on to half-inch sisal rope. The fillet knife crunched aggressively to 200 cuts very quickly. The challenge on my part was to watch for the blade flexing. It cut great but it was weird feeling the flex. It seemed to slice smoother toward the last 50 cuts. I was probably knocking the newness off the Power Strip.

Curved Fillet Knife Processing Game

Hunting season was in full swing where I live at press time, and I like cooking fresh venison backstrap. The fillet knife zipped through the meat quite smoothly and cleanly. With the temperature at 22°F, the handle stayed tight in my cold hand.

I found some whole tilapia to fillet. After thawing, it was ready for action. The knife excelled at preparing the fish. It glided along the bones in short order. Dang, I needed this blade when I was younger working for a commercial fish house in Wisconsin! I went back in to thaw out my fingers and fry some fish.

The final test was back to slicing the copy paper. What a difference from the first test. The edge was smooth slicing and a lot cleaner in the cuts. The more you use the knife the better it gets. Perpetual Edge all the way!

Final Cut

I’m impressed with the Relentless blade’s ability to stay sharp by itself. It’s very well suited for saltwater and freshwater use. Hats off to the Relentless crew. I would have to do a lot more testing to come up with any changes. I’m waiting for a Relentless hunting-style knife to come out soon. Stay tuned to the Relentless website (see below) for more details.

More Outdoors Knife Reviews:

• Presnell Utility Hunter Review
• Peltonen M07 Ranger Review
• Bob Dozier’s Skinner Review
• Montana Knife Co.’s Marshall Review