Disclaimer: I'm a metallurgist and not a historian.

I'd say that it's more of a question of consistency. Could historical swords be made that equal or surpass today? Absolutely, but you're talking about a minority of them. Today we can melt 50,000 lb heats of steel that will all have uniform quality and every sword made from that will have consistent quality.

I know a lot more about recent (20th century) advances in steel making than I do about historical ones but in the last 60 years or so, we've made huge strides in quality of steels. Added to that, there are constant developments of new alloys, even new alloy families, that could be turned into blades.

I think you need to look into the knife industry more than the sword one, there's a lot more demand (and hence R&D) today going into that sort of sector. Comparing modern knives to historical ones would be a better method of comparing the metallurgy of today and the past.

I can't provide a lot of information on the history of steel but if anyone has anything to add, I can help contrast that with today's technology.