SFWG Study Hall

I always start with the wikipedia articles - you can get rubbish, but they usually provide a decent backgound that is easy to understand.

http://en.wikipedia.org/wiki/Scimitar
http://en.wikipedia.org/wiki/Sword

Then I look for any other websites that may have turned up in my search that look interesting.

For medieval warfare, I always start at Stefan's Florilegium
http://www.florilegium.org/ (look under 'Combat' on the LHS menu)
and any other relvant SCA sites. I find that they tend to lead on to more websites, and my search expands from there.

For the scimitar, don't forget to look at the Asian fighting styles, as opposed to the Occidental ones.

I hope this helps you in some way.