Tom,
Ok, so I'll take out my simplification machete chop the idea to pieces:
1) One stat for brutality-gentleness continuum. Brutal characters get bonus for brutal actions and a slight damage bonus in melee combat. Gentle characters get bonus in courtier type activities. Brutal characters are not as efficient with courtier type work and vice versa.
2) One stat for player given reputation. Good reputation would be beneficial in lordship positions and perhaps in the realm council (especially ruler). In essence good reputation would work towards making a statement about "who would you like to see in leadership positions". Comparisons would be made on realm level. Not sure what infamy would accomplish here, nor if more is even required than "negative or controversial stigma".
3) One stat for combat activity. The more you have it, the more troops you can command. Call it experience or whatever, but basically the more you march with you men, the better you are at commanding large groups of men. Reduces gradually when not gained regularly.
4) One stat for valor. You gain it when you assault cities and strongholds successfully. Valor levels are compared individually for each realm and are always relative values. Only top 50% valorous characters can recruit cavalry, and only top 20% can recruit special forces.
The good-evil continuum fleshes out some personality for the character, and here the ends balance out each other. You can't have it all. It's good to be a brutal lord on the fringe regions that need high control, but being nice has its benefits too. Player given reputation encourages rulers and dukes to appoint lords that the noble population in general sees as fit for leadership (if the candidates are otherwise equal). Infamy gives bad reputation which gives nice first impression effects for real social interaction. The two military stats encourage participation in war, and since they are reduced over time (especially combat activity), it works a little like "too much peace". Monsters and undead wouldn't count here.
There might be room here still for a third combat stat to measure the success of a character in battles, but as you said, that may be tricky to evaluate.
