Naso Diabolus Leviathan 300mm Slicer Review: A Massive Knife With Surprising Finesse

Introduction

Every now and then a knife arrives that changes the rhythm of a review. This one did. It is, without exaggeration, the most massive kitchen knife we have had in the kitchen for testing: a 300mm slicer from Samuel, the maker behind Naso Diabolus, working out of a small home workshop in the Adelaide Hills of South Australia. He forges all his own blades and billets in-house, and this is his knife number 20.

If that number surprises you, good. It surprised us too, because the finish quality on display here is the kind of thing many experienced makers only develop years later.

Who This Knife Is For

Samuel describes this as a sujihiki-esque meat slicer, and the intended job is clear: long, clean strokes through protein. This knife suits someone who cooks larger cuts at home, wants a statement piece with genuine performance behind the aesthetics, and appreciates the details that separate a polished handmade blade from a factory one.

It is also a good match for buyers who want to support a rising maker early in their career. The brand name itself has a great backstory: Naso Diabolus references St. Dunstan, the patron saint of smiths, who realised a visitor to his shop was the devil in disguise, heated a pair of tongs, grabbed him by the nose and threw him out the door. Naso, meaning nose.

First Impressions and Unboxing

The packaging experience was a highlight in itself. Beyond the knife roll, the delivery included painted artwork from the maker’s children, including a paper saya that now lives with the rest of the collection. Personal touches like that are hard to put a price on.

The blade itself is a spicy white core steel sandwiched in Sanmai with in-house laminated antique wrought iron. The look is strikingly high contrast: rustic textured flats, a Kasumi wet-stone worked bevel, and a shiny exposed core steel line. The handle is ringed western maple with a ringed bella sapwood spacer, and light absolutely dances across it, especially on the right side where the D-shaped handle flares outward.

Size and Design

Context matters with a blade this long. Next to a 225mm carbon steel slicer, the length difference is obvious, but it is really the blade height that jumps out. Compared with a 300mm Yanagiba, a knife that shares the same low-drag design philosophy, the extra height is immediately apparent. The blade and handle both feel large in every dimension.

Despite that scale, the finishing details hold up beautifully. The spine and choil are fully rounded for comfort, the tip is thin and usable, and even the handle butt is chamfered. These are the details that make long cutting sessions comfortable.

Cutting Tests: Vegetables and Fruit

A 300mm slicer is meant for protein, so vegetables became an unfair but revealing test. A wedge test on green cabbage was tough going, as expected, but that says more about geometry than sharpness. More telling was the cherry tomato: edge bite genuinely impressed, with clean bites through tomato skin without the knife wanting to roll away.

A giant zucchini became pure fun, with long even slices coming off the high-polished edge. Rocking sweeps through shallots and herbs worked well thanks to the belly profile, and the 26C3 spicy white edge felt extremely robust throughout. At no point did it feel like it wanted to bend or chip, even with the inevitable food stick that comes with a blade this tall.

The Real Job: Slicing Meat

This is where the Leviathan earns its name. Slicing through multiple rows of riblets at once was effortless: great weight, clean cuts, zero fuss. The panettone session, shared with a guest who had never held a knife quite this long, turned into an accidental demonstration of how forgiving and enjoyable the blade is even for a first-timer.

The annual bone-in prime rib roast was the true stress test. Even at 300mm, the knife felt small against that roast, so a little sawing was inevitable, and striking the bone while removing it was a reminder that a slicer is still a slicer. But the next-day slices off the chilled roast were genuinely stunning: long, even, and clean.

Things to Consider Before Buying

Honesty matters here, and there are a few design choices worth weighing. The blade height could be around 25% lower to reduce drag, and a 25% smaller handle would match the blade better. The D-shaped handle is well executed, but the flaring on the right side adds to the oversized feel. A thinner primary bevel would also help it do its intended job even better.

None of that changes the fundamentals. The knife is built like a tank, with a choil bevel that evokes a hard-use blade: resilient, bone resistant, and confidence inspiring. The handle construction, blade finish, exposed core steel, steel choices, and fit and finish all deserve nothing but praise. The patina that developed over testing added character, and the perfectly chamfered spine, choil, and handle show a level of care that is rare this early in a maker’s career.

Buying Advice

Buy this knife if you want a large handmade slicer, value impeccable finishing as much as cutting performance, and like the idea of getting in early with a maker who clearly has a bright future. Skip it if you want a nimble, low-drag sujihiki in the traditional mould; the generous height and large handle will feel like too much knife.

Conclusion

Knife number 20 from Naso Diabolus is not a fluke. It performed surprisingly well across nearly everything it was asked to do, from cherry tomatoes to prime rib, and its craft details are genuinely exceptional. With slightly reduced blade height and a slimmer handle in a future version, this maker would have something truly special. As it stands, Leviathan is a confident, characterful slicer that earns its place on display, even if it does not fit on a standard knife rack.