A Samurai sword set, or daisho(pair), consisting of Katana(long sword), Wakizashi(short or auxillary sword), and a tanto used for commiting seppeku.
The Katana, or "Samurai sword", as it's more commonly known, is considered by some experts to be the most lethal cutting weapon known to Man. Hailing from Japan, where it was used in the Middle Ages by the Samurai, the average Katana is about 40 to 50 inches in length, with a gracefully curved blade ranging from 30 to 36 in., typically. The hilt is always two-handed, usually a foot long, give or take, and is usually wrapped with cotton, silk, or some other organic fiber(if the blade is traditional). A traditionally forged katana is created by taking soft and hard iron, and hammering/folding them together in a forge laced with carbon dust to create hundreds, and sometimes thousands, of layers of steel. The Katana is capable of cutting through virtually any organic fiber you can imagine; skin, bone, and tendons are no match for this weapon.
However, it is not authentic katanas that concern us right now.
It is the imitations.
The sword market is being flooded by millions of cheesy fakes and reproductions flowing from China and Taiwan that are made of inferior stainless steel, and cost anywhere from 10 to $60. These weapons are everywhere; the Internet, sword/knife magazines and catalogs, and even pawn and curio shops. Some fakes are quite clever, so I have compiled some criteria that a sword must meet before it is a true katana.
1. The notare(no-tah-ray) is the distinctive wave design that runs along the cutting edge of a real katana. One thing to look out for is a Notare that is perfectly even, all the down. On a hand-forged sword, the wave will be gentle, subtle and, well, wavy. However, if it stands out on the blade, this may indicate that the notare is acid-etched, or that the sword was produced from a machine factory, thus making it totally inferior to a traditionally crafted sword.
2. On the back of the blade(the dull edge), there should be lots of thin, hard-to-see lines running down all the way to the tip. This indicates that the sword was traditionally forged, and folded, making it stronger. The lines indicate the layers of steel.
3. The feel of the sword itself. This criteria is a tad vague, but with practice and experience, you should be able to master it. Take the sword out of the scabbard and just hold it. A machine-made hunk of junk will feel too light or two heavy, but the average katana should weigh somewhere between two to four pounds.
4. Shopping online: when shopping for a sword on the Internet or in a catalog, look very carefully at the fine print. Was the sword heat tempered? Was it hand-crafted? And what kind of steel was it made of? If it says "heat-tempered 440 steel", walk away; 440 is just stainless steel. Also, make sure(obviously) that it does not say "For display purposes only". Note: two companies that make combat-ready, traditional swords are Hanwei and United. I happen to own a United Black Damascus katana that came razor-sharp with a beautiful lacquered scabbard(which has since been damaged when I accidentally knocked it off the top of my television; when displaying a sword in your residence, make sure it's out of the way).
While this is by no means a complete guide to finding a good sword, this should aid you in discerning the real from the fake.
May this guide aid you in every way possible.