I dont know if this will help bit it will be a start.
The Origins of Saluting
by WOFF Chris Dunne,
Air Force Warrant Officer Disciplinary
There are a number of origins of the military greeting of saluting. In the age of chivalry the knights were all mounted and wore steel armour, which covered the body completely. When two friendly knights met it was the custom for each to raise the visor and expose his face to the view of the other. This was always done with the right hand, the left being used to hold the reins. It was a significant gesture of friendship and confidence, since it exposed the features and also removed the right hand from the vicinity of a weapon (sword). Also in ancient times the freemen of Europe were allowed to carry arms: when two freemen met, each would raise his right hand to show that he held no weapons in it and that the meeting was friendly.
The Coldstream Guards appear to have been the first to depart from this practice as a Regimental Order of 1745 reads: �The men are ordered not to pull off their hats when the when they pass an officer, or to speak to them, but only to clap up their hands to their hats and bow as they pass them�.