Long before the tourney started, I'd tested out how experience was split, and it came out that the commanders in the same army equally split the experience no matter how much they contributed to the kills. So if you had two commanders in one army, and one had 1 knight under him and the other had 100 knights under him, the experience gained was still equally split.
On the very first day of the tourney, I had stacked two armies: one with a few knights under him to activate the stone and 1 with my full army under him. Never having used messengers before, I had assumed I could specify that only the "place holder" army would be recalled. I ended up leaving him on the stones rather than lose out on the night for the other army, and it looked like the experience was equally split between the two commanders.
More recent tests, however, do make it appear that this has changed. For stacked armies, I suspect it does have to do with the % of the total attack or defense power contributed by the army, but I'm still testing this.
I don't suppose a knowledgeable GM would care to confirm how experience is split?
Edited by Mara Zira - 29 Dec 2011 at 20:29