TWG, I think that the problem is that there are just too many different types of Western swords for any smith to have mastered how to size them. Take the rapier, for example. At one point, the theory was that the longer the blade, the better. This resulted in blades on rapiers exceeding 40"-45". This is a good length for a two-handed broadsword, if I am not mistaken. It got so bad that Elizabeth I passed a law limiting sword length to 36", IIRC, and had her law enforcement types equipped with devices to break the blades off of offending rapiers at the prescribed length. One of the problems that these extra long rapiers were causing was the personal offenses taken when one party unintentionally "goosed" another with his sword scabbard, resulting, of course, in a duel to settle the point of honor.
Just think of the many, many different types of swords that have appeared throughout the history of the West, from the xiphos and machaeira of Ancient Greece to the smallsword and saber of the 19th Century, and you'll get some idea of what would lie in store for a smith to learn. Heck,I know guys who have spent their entire lives studying nothing but the shortswords of Ancient Rome or the Norse-pattern broadswords and still have things to learn about them. And, I daresay, that the same is true of the true students of the Japanese swords.