Here's a dev comment i saved, discussing kills/valour and how it worked in STW and MTW:
Quote Originally Posted by longjohn2
I've discussed kills and valour before. Suffice to say that they are bunch of factors that determine how many kills a particular kill actually accounts for. They were put in for Shogun, so have something of an honour based theme. They depend on relative honour levels, social status, and such factors as whether the victim was killed in melee, shot, or hacked down while running away.
I'd be a little surprised if they deviated away from their "honour based theme". Killing a peasant shouldn't be worth as much xp as killing an heir. Same thing with running down a router or hacking a woad warrior in battle.