I could dig around for some old threads but they do relate some practical notes on keeping swords sharp in the 19th century. In particular, some of the older SFI threads regarding this very topic. Files issued for keeping edges sharp, being gentle during insertion in metal scabbards, not using your sword for spitting meat over the fire, stuff like that.
As to last American use of swords, one example makes me wonder a bit about this particular Patton. Also in my files are pictures of the Peking horse marines, with their nickeled baskets. There was also a note over on Blade Forums somewhere about an American officer in Viet Nam dropping from a huey with sabre in hand (I have no hard reference for that, nor the sword type). I'll see if I can dig up that Boer War sharpening image as well. Well, my files sure are in a state of mess right now but here also some Prussians sharpening on some stone steps. Ok, here are the Boer boys.
Here is the old Don Nelson Thread
http://www.swordforum.com/forums/showthread.php?t=5896
Jean's notes are always fun to follow.
Cheers and Happy New Year
GC