I know that most of the posts in this thread are tongue-in-cheek, but I actually am an expert in Japanese swordsmanship, with seven years practice in a tradition that dates back to the mid 1500s.
This is me at the 4:40 mark, demonstrating Yagyu Shinkage-ryu kenjutsu.
On the subject of European vs Japanese swordsmanship, they are more alike than different. Which is not surprising given that they are both involved in humans using two-feet of sharpened steel to inflict damage on another human, typically armored. Cleaving blows are not a primary tactic in classical swordsmanship that dates back to the actual Warring States period. In these traditions, the goals are cuts and thrusts to the weak points of armor where vulnerable arteries are located. It is not expected that you will ever cut through limbs or the like. In training, big cuts are often emphasized because in the course of actual combat, the influx of adrenaline will reduce the effectiveness of fine motor control, and movements can become small and tentative. The idea is training big will ingrain full, fluid movement, and ideally counteract the psychological and physiological effects of increased adrenaline.
Here are some examples -
The first kata
here is for armored combat. The cuts are all to weak points in the armor -- in particular the "winning" side cuts inside the wrist, where there is a seam in the armor, and the ulnar artery.
This clip is from a different style. It's in Japanese, but the demonstration should be clear enough.
Kendo, unfortunately, is not a good example of true combative swordsmanship. An explanation of why would be too long here, but suffice to say that it intends to focus on certain aspects apart from the technical minutia of actual combat with swords. It thus bears as much similarity to that as modern Olympic fencing does to the live blade duels of the 17th century.
On the subject of katana themselves, the history of the katana is a downward progression through the centuries. The finest blades were made during the Kamakura period (1185–1333). These were essentially cavalry sabers, made for slashing from horseback. This is generally considered when the art of swordmaking in Japan reached its peak. Such swords are extremely rare and highly, highly valuable. Most are considered national treasures, and I'm not sure there are any in private possession outside of Japan. The swords of the Sengoku period (1467–c. 1573) where also finally made, but this was a time when mass production of swords was required, leading to a loss of some of the fine techniques of swordsmithing, as quantity was emphasized over quality. Most swords of high value possessed by private collectors are from this era. The swords of the Edo period (1600-1868) where of even less quality, as it was a time of long peace, when swords became prized as status symbols rather than tools of war. These are the most common katana one finds in collections.
Many swords outside of Japan are gunto -- military swords made during the 20th century. These were machine cut, not forged. They are also crappy. Finally, there are gendaito -- modern forged swords. Quality on these can vary. They are invariably made for either decoration, for cutting practice, or for iai (sword-drawing practice), and not for combat. The remaining smiths may not even know what is required to make a katana for actual combat, since those techniques have not been in demand for over 400 years. Still, a low-end modern forged sword is generally going to run around $12,000 or so.
All live blades must be registered. Swords considered of cultural importance (most historic swords of good quality) are not allowed to be taken out of Japan.
I do not know what kind of sword mach1.9pants' friend had. It may have been a cheap wall-hanger (katana shaped hunk of iron), it may have been a mogito (non-forged, non-sharp blade made of stainless steel), which can vary widely in quality, it may have been a historic sword from the Edo period, or possibly even the Muromachi period. Perhaps even a modern, forged sword. I do know, however, that I've handled a katana from the Sengoku period, and it was absolutely wonderful, with impeccable balance that gave it an unbelievable lightness. It could easily be wielded with one-hand, and so if it were a D&D weapon it would be a versatile finesse weapon. Not all katana are like that. Heck, not all European two-handers are like that. But some are.
