The first things in english that come to my mind are (the first mostly in english:
-"The Journal of Roman Military Equipment Studies", which has a few articles about swords in it's various volumes.
http://www.jrmes.org.uk/

and "Roman Military Equipment" by M.C. Bishop & J.C.N. Coulston
http://www.romanmilitaryequipment.co.uk/

I also found an arcticle on JSTOR, but can't acces it from here, but it sounds interesting:
"Study of the Metallography of Some Roman Swords"
http://links.jstor.org/sici?sici=006...3E2.0.CO%3B2-J

The numbers for the legionary equippment posted above are from "Die Legionen des Augustus" by Markus Junkelmann, very detailed but only focusing on augustan legionary infantry and rather old now.