All right. I may sounda little obsessed, but after checking the historical manuals I can't help wondering if anyone has gone to such lengths as to publish an interpretation of an Italian master's two-sword techniques, whether on its own or a spart of a more extensive work covering the whole of the master's teachings. Does anybody know of such publications?

I am unaware of anything published based off of historical research, unfortunately, as it is a very interesting style. I've done only enough of it to know I don't like doing it ;) , but it's still very interesting. The only stuff I'm aware of are handouts I've seen where people have made up their own modern systems for more "sport" oriented types of fighting, and not based off of actual histoircal fencing.

The main source is Di Grassi who states that unless you can use a sword as well in your left hand as your right then you should give two swords a miss. Based on this I think that most researchers into swordsmanship of this period have decided that since they can't do the style really well with their dominant hand, let alone their non-dominant one, doing two swords would be putting the cart very much in front of the horse.

Cheers
Stephen

What is the earliest mention of due spade? A renaissance thing?

The earliest mention I'm aware of is in Antonio Manciolino's Opera Nova--1533 if I'm not mistaken--and it's the one I used for the reference of my clumsy attempts at emulating the style. Marozzo's 1536(?) work also had a mention of it. I don't knwo if there are any earlier sources, though, and I don't really think so since due spade is such a one-on-one dueling style. I can't imagine it being effective on, say, a massed battlefield.