I think his question is actually rather similar to thisthis one.
In the end a single lightsaber wont make much difference. Yes it will be great for morale boosting, and it will be hands down the most effective fighter on the field, but be able to beat armies. It wont be able to stop 1000 arrows flying towards it. The users wont have the force so they wont be able to sense that guy sneaking up behind them.
Ultimately if it was really used in combat it would probably change hands a lot. if it wasn't used in combat it would be basically like a relic of some saint (though would be the most awesome relic ever), used for morale boosting and such but no tangible effect on battle day.