Koenig Arius Marbled Blue Carbon Fiber, Gen 4 in CPM 20CV
The Koenig Arius Marbled Blue Carbon Fiber is a Gen 4 Arius with a CPM 20CV blade. The show side is marbled blue carbon fiber over a titanium frame lock. It runs 8.5 inches open at 4.0 ounces. Condition is excellent, with no signs of wear or blemishes.
The Arius is Koenig’s flagship, co-designed with TJ Schwarz. It has a reputation for machining precision and a flipping action collectors describe as addictive. This is the fourth generation of it.
Koenig works in what the trade calls semi-custom production, which places the Arius between a factory knife and a one-off custom. Our guide on how to choose a custom knife covers where that line sits.
Bill Koenig, and a Shop Built in Boise
Bill Koenig made his first knife as a Boy Scout. He bought knives, took them apart and cleaned them. His father drove him to blade shows, though he knew little about knives himself.
By the fall of 2016 Koenig had saved enough to lease a building in Boise, Idaho. He filled it with a new Haas CNC, a surface grinder, a tumbler and a sandblaster.
Every Koenig is still machined in house in Boise, and each carries a limited lifetime warranty. See the rest of our folding knives from American shops working at this level.
What Changed in the Arius Gen 4
The clearest Gen 4 change is weight. Koenig milled lightening pockets into the inside of the handle scales. That takes nearly an ounce off compared with earlier versions. You cannot see them from outside.
The rest of the design carries detail that is easy to miss. The pivot uses a D-shaped female side, so it does not rotate when you adjust it. The clip carries a hole aligned with the lockbar relief cutout, and the lockbar is jimped for traction.
It runs on ceramic bearings. The flipper tab is large enough to act as a finger guard once the blade is open. A thumb slot through the blade lets you open it quietly by hand. Compare it against the Arius Gen 4 in MagnaCut we carried previously, the same generation in a different configuration.
CPM 20CV, and Why It Sits Beside M390
The blade is CPM 20CV, a Crucible powder metallurgy stainless with high chromium and high vanadium. The chromium gives it strong corrosion resistance and the vanadium carbides give it long edge retention.
It is also very close in composition to Böhler M390 and Carpenter CTS-204P. The three come from different mills and behave almost identically in a knife. That makes this blade a near twin of the steel on the Koenig Arius in M390 we have in stock.
The finish is Koenig’s brightwashed treatment with polished flats. The flats are polished, and the bevels around them carry the brighter washed finish. The blade reads in two tones as a result. The grind is hollow and the profile is a drop point with an upper swedge.
The Koenig Arius Marbled Blue Carbon Fiber Scale
The show side is smooth marbled blue carbon fiber. Instead of a regular woven check, the blue runs through the black in irregular swirls. No two scales carry the same figure. It is finished smooth rather than textured.
The lock side is 6Al4V titanium. Putting carbon on the show-side takes weight off without touching the durability of the titanium lock-side.
The backspacer and the 3D-milled pocket clip are titanium, and the clip is set for tip-up right-hand carry.
Condition and What’s Included with This Koenig Arius Marbled Blue Carbon Fiber
Condition is excellent. There are no signs of wear and no blemishes. We inspect every knife in hand before we photograph it. Our published grading standards let you check this description against what arrives.
It came out of a collection rather than direct from Koenig. The certificate records the model, the blade, the handle materials, the generation and a date of November 24, 2022. Read how we handle provenance on pieces that arrive with their paperwork.
- Koenig Arius Gen 4 folding knife
- Original Koenig box
- Microfiber cloth
- Signed Certificate of Authenticity
Koenig Arius Marbled Blue Carbon Fiber Specifications
The model, blade, handle materials, generation and date are taken from the signed certificate.
- Overall length, open: 8.50 in
- Blade length: 3.50 in
- Cutting edge: 3.25 in
- Closed length: 5.125 in
- Blade material: CPM 20CV
- Blade style: Drop point with upper swedge
- Blade grind: Hollow
- Blade finish: Brightwashed with polished flats
- Lock type: Titanium frame lock with steel lockbar insert
- Action: Manual
- Deployment: Flipper tab and blade opening window
- Pivot: Ceramic bearings
- Handle, show side: Smooth marbled blue carbon fiber
- Handle, lock side: 6Al4V titanium
- Backspacer: Titanium
- Pocket clip: 3D-milled titanium, tip-up, right-hand carry
- Weight: 4.0 oz
- Generation: Gen 4
- Date made: November 24, 2022
- Country of origin: Boise, Idaho, USA
- Condition: Excellent, no wear or blemishes
- SKU: 00209-KOE-ARIUS-GEN4-20CV-BLUECF-20221124
This piece is preowned and came from a private collection. Browse our other preowned knives.
Video Description: Gen 4 Arius in Blue Carbon Fiber
The Koenig Arius Marbled Blue Carbon Fiber is a preowned Gen 4 Arius in excellent condition. The blade is CPM 20CV, hollow ground to a drop point with an upper swedge and brightwashed with polished flats. It measures 3.5 inches with 3.25 inches of cutting edge. Koenig built it in Boise, Idaho, and the certificate dates it November 24, 2022.
The show side is smooth marbled blue carbon fiber over a 6Al4V titanium frame lock with a steel lockbar insert. It runs on ceramic bearings and opens on a flipper tab or the thumb slot through the blade. The backspacer and 3D-milled clip are titanium. Overall length is 8.5 inches open and 5.125 inches closed, at 4.0 ounces. It ships with the original box, cloth and signed certificate.
Frequently Asked Questions
Is CPM 20CV actually different from M390?
Barely. CPM 20CV from Crucible, M390 from Böhler and CTS-204P from Carpenter are very close in composition. All three are high chromium, high vanadium powder stainless steels, and in a knife they perform almost identically.
The practical differences come from heat treatment, which is the maker’s work rather than the mill’s. Expect long edge retention and strong corrosion resistance. Expect it to take more time on a stone than a simpler stainless. The Arius in M390 we have in stock runs what is effectively the same steel.
Why carbon fiber on one side and titanium on the other?
Because only one side has to hold the lock. On a frame lock the lockbar is cut from the frame itself, so the lock side has to be titanium. The show side carries no lock, so it can be carbon fiber.
Carbon fiber is lighter than titanium, and it lets the show side carry a pattern. Combined with the internal lightening pockets, it is why a full-size 8.5 inch folder weighs 4.0 ounces.
What did Gen 4 change on the Arius?
The clearest change is weight. Koenig milled lightening pockets into the inside of the handle scales. That took nearly an ounce off compared with earlier versions.
This generation also uses a D-shaped female pivot that does not rotate when you adjust it. The pocket clip carries a hole aligned to the lockbar relief cutout. It runs on ceramic bearings, with a steel insert in the lockbar.
How does this Koenig Arius Marbled Blue Carbon Fiber compare with the other Arius knives here?
Each Arius we have listed runs a different steel. The Gen 4 we carried in MagnaCut had a distressed DLC blade and Carbon Fiber Corda. The pattern milled titanium Arius in stock runs M390 with Timascus upgrades. This one runs CPM 20CV with marbled blue carbon showside.
Because 20CV and M390 perform almost identically, the choice between this and the in-stock Arius comes down to the handle. One pairs carbon fiber with titanium, and the other is pattern milled titanium with Timascus accents.
Is a Koenig a custom knife?
Not in the one-off sense. Koenig works in what the trade calls semi-custom production, or mid-tech. Knives are machined in house in Boise to a very high standard and released in defined configurations.
That places the Arius between a factory knife and a true custom. Every Koenig is backed by a limited lifetime warranty.
Does We Buy Knife Collections actively support the broader knife enthusiast community?
Yes. Based in Jacksonville, Florida, We Buy Knife Collections is a curator and purveyor of fine custom made folding and fixed-blade knives. We are dedicated to the high-end custom knife community and we support knife rights advocacy.
Following our commitment upgrade in April 2026, we are proud to hold an AKTI Premier Membership, supporting the American Knife & Tool Institute’s vital advocacy and lobbying for knife owners, makers, and the future of the industry.
Buy This Koenig Arius Marbled Blue Carbon Fiber
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