Ka-Bar combat knife (US Marine Corps)having long sword or bigger melee weapons can draw attention from law enforcers, these are allowed items wrt household use, so better learn within the line without drawing much limelight than getting items confiscated by PD.
Ka-Bar - Wikipedia
en.wikipedia.org
The KA-BAR combat knife is often considered one of the deadliest close combat weapons in the world. Developed by the United States military in the 1940s, the KA-BAR features a heavy, durable 7-inch blade that can easily pierce flesh and bone. It has been used extensively in close quarters combat by various military and law enforcement units due to its effectiveness as a stabbing and slashing weapon. While there is some debate, many experts agree the KA-BAR's combination of size, weight, and sharpness make it one of the most lethal hand-to-hand weapons available.
Jagdkommando Knife (Austrian Special Forces)
With its distinctive twisted blade design, durable construction, and versatile uses, the Jagdkommando knife is a great choice for outdoor activities, self-defense, and combat situations.
In a knife fight this weapon is really only effective if you have the element of surprise... This knife will not maim someone, it will kill them. Hit the femoral artery and a team of surgeons couldn't save you.