Being something of a sword geek/medieval nerd, I found several really great resources for modeling historically accurate swords. The resources I found include a full breakdown of the Oakeshott typology and the proper proportions and dimensions of both arming swords and longswords. The geometric porportions are based on measurements taken of historical swords, information found in medieval smithing manuscripts, and informed conjecture based on the geometric principles of gothic architecture from the medieval period.
I just wanted to pass this stuff along to any modelers on here who might be interested in historical weapon modeling, like I am. I hope it helps.