A recent discussion on Fanaticus was questioning a rather unusual Sabre grip used when delivering a thrust during a cavalry charge. The method saw the little finger looped over on the other side of the grip to the other three fingers.
A quick search came up with an excellent collection of 19th Century swordsmanship resources from the Schola Forum: http://www.fioredeiliberi.org/phpBB3/viewforum.php?f=22
I should also mention the Schola Gladiatoria Victorian Marital Arts page as an useful resource: http://www.fioredeiliberi.org/victorian/
Among these is the Cavalry drill and sabre exercise: compiled agreeably to the latest regulations of the War Department, from standard military authority by George W Patten (1862).
Below are some of the key plates that may be of some assistance.
1. Instructions in the small sword exercise (Patten, 1861)
In his subsequent work on Sabre and Cavalry drill (1862), Patten refers back to his earlier work on infantry tactics for anything not covered in this later work. I found this description of the sword grip.
Patten, G. Washington. (1861). New York: J.W. Fortune.
Reproduced at: http://babel.hathitrust.org/cgi/pt?id=uc1.b4236832
2. Sabre Drill, Patten 1862
|See 'Present' (middle of page) for description of sabre grip. This is the only reference I found to the position of the little finger when gripping a sabre.|
The following pages then go on to describe the method used to practice the thrust of a sabre.
Cavalry drill and sabre exercise: compiled agreeably to the latest regulations
of the War Department, from standard military authority ...
Patten, George Washington, 1808-1882.
Richmond : West & Johnston, 1862.