Military can't be stressed enough, and our own personal skills can't be stressed enough. Without a battle, there would be no noble house of Stone to begin with. Military is the raison d'etre.
I'm not interested in archers fighting fully from horseback, since that is a difficult skill, but there's no reason not to give all our archers and skirmishers horses. This speeds them up outside of battle at the very least, and gives them mobility on the battlefield as well. The skirmishers can actually be light cavalry of a sort, screening the deployment of our rangers and archers, who travel by horse and deploy on foot.
Archers and Rangers -- 10 man squad
Armor: Brigandine cuirass, Kettlepot helms, leather elsewhere
Arms: Longbows of a 150 lbs draw, 300 yards range, arm-strapped bucklers, and shortswords
Equipment: small fast horses, saddles with holders for longbow and three sheaves of arrows.
Skills: High draw-weight Longbow skills, Woodcraft, Trapping and Ambush, decent hand-to-hand and adequate riding skill
Skirmishing Light Cavalry -- 5 man squad
Armor: Brigandine and chain
Arms: Spears, ten throwing axes, medium targe
Equipment: Fast light horses
Skills: Above average riding skills, combat riding training, excellent melee, throwing, and shield skill
Support and Engineering -- 1 per 10 soldiers
Armor: leather
Arms: short sword, buckler
Equipment: light horse team on light cart, 5 shovels, 5 axes, 5 10lbs hammers, and thin wooden panels and wooden stakes.
Skills: adequate teamster skills, above-average carpentry and other crafting.
Tactics: The archers are the backbone, the light cavalry skirmishes and delays any forces threatening the archers by skirmishing and harrying from the flanks as the archers rain arrows into the center mass; and the support can pass out equipment to the others and direct them in building improvised pit traps, stakes, barriers, pavises, etc. Given enough time, the force can dig in quite sturdily.
Tell me what you think.
Also, let's not visit Marna, because we want to be an ambitious young nobleman that she dreams about, not her puppydog. Writing is fine.