If one wants an authentic replica sword, you must look for (at least!) the qualification of "tempered" or "battle ready," as there are a lot of junk-replica "wall hanger" swords out there. Most of the hand-forged swords--built just like they were in medieval times-- (if they aren't custom built) are made overseas, although, Quebec has a decent forger (but whose swords, while indestructible, tend to be heavy...). www.darksword-armory.com )
Windlass of India ( www.museumreplicas.com, makes very fine swords (including ceremonial swords for the US military) which match the quality of the middle ages, at a reasonable cost (that would be under $300).
If cost is no object, swords BETTER than those of knights can be had from some American makers--Albion (above) is the best... ( www.albion-swords.com ) made from impeccably machined steel alloys. To my mind though, these are just too perfect... to be unrecognizable to a medieval...besides costing upwards of $900.
The maker of the sword I pictured earlier (and imediately above) (a copy of King Henry V of England's sword from the early 1400s, categorized an Oakshott Type XVIII) is by another excellent hand-forged maker, Generation 2, of the Philippines www.imperialweapons.com.. This particular model is considered a breakthrough, as it is a very close replica of an actual museum piece, at (just) $260. Before this sword, exact replicas were $500 and up.
Hanwei of China ( www.casiberia.com ) also produces authentic hand-forged swords at reasonable prices. Like most of the sword makers above, they produce various designs, Asian, Medieval, or, as you like, ancient Roman designs (below).
Tempered/battle ready swords can come sharpened or unsharpened (a bone of contention among some scholars--as both kinds exist from the middle ages). Probably a medieval sword maker produced an unsharpened sword--which could then be used for much needed practice--and only was sharpened up for serious battle. Modern (real) sword makers do the same.
Since a knight's quality sword of the middle ages was known to have cost the price of a house... $260 up to a couple thousand dollars today, can be seen as a great bargain!
Personally, I got into swords through an Australian website called the Sword Buyer's Guide (www.sword-buyers-guide.com ) They have some 10% discount coupons available there (and on 300 dollars $30 is nothing to sneeze at) and the guy running it seems very knowledgeable without being a snob--as some sword collectors certainly are. He specializes in the under $300 variety of real, usable swords.
Honestly, I bet his expertise has something to do with the hideous government gun-grabbing now prevalent in Australia. In these uncertain times, besides guns, I actually do think having a real sword around isn't a bad idea.
The best places to look at swords online are actually NOT the manufacturers/wholesalers sites above, but at dealers--who often have the latest models and at better prices. Cult of Athena and Arms of Valor are considered a couple of excellent dealers, where you can see all the various brands--however they do sell junk wall hangers as well as real tempered ("battle ready") swords.