the question fetches up against the right tool for the job problem. While swords in the past where developed within a framework of technology, culture and warfare. Swords today are not really wielded in anger only occasionally in lunacy.
So set adrift of the cultural heritage, free to employ the breadth and width of steel technology, and without the reality of warfare, what is the perfect sword?
Think
George already answered that one.
But seriously, what standards are to be employed, beauty? saleability? ritualized combat?
l'art pour l'art seems the most applicable, a demonstration of both beauty and master craftmanship.
And of course beauty is highly subjective, one of the most beautiful blades Ive ever seen was a beveled leaf bladed short sword lacking a guard (which seemed unnecessary given the hilt much like a Dirk)