So, my party has just been sent to war (I'm the GM) and I've asked what their general plans were (none of which were really about winning the war I presented the idea as a way to make money and prestige in that order). One of them stated that he intends to turn the men and women under him into butchers, killing machines. Harsh training and all that.
Now I intend to give my players all leadership for free when they reach lvl 7 (don't worry about the cohorts, it's not a normal game, the cohorts will be very powerful servants and agents, not really extra PC's). And I want that player to be able to draw on the soldiers that he trains as followers, however that means that they shouldn't gain levels, because then they would be too high level to be followers.
So I'm putting it to you fellows how should I represent the training that these soldiers undergo?
I've thought of retraining their hp to max (warriors don't get max by default lvl 1). What else could I do?
Morale, Circumstance and Competence bonuses to attack rolls, damage rolls and saves could reflect motivation, good leadership and better training. Since they stack, a more well rounded leader will have more superior troops. Masterwork and upgraded gear could also affect these soldiers' capabilities.
Imagine going up to a +5 for these bonuses... very effective soldiers even if they never increase in HD. Their "+2" to attack rolls could eventually be a +17(+18 with Masterwork)! Now they can be deadly but still easy to kill.
I like the Max HP idea! Another one is maybe instead of advancing HD, you could (sparingly) grant troops a bonus to an ability score or a bonus feat like Weapon Focus.
In any case, this training should take weeks or months and possibly extra funding. I could see that some bonuses could only be acquired or allowed to increase above a set cap, like going above a +2, by surviving multiple battles. Training can only make a certain quality of warrior... it takes real battles, fought and won or survived over time, to advance them into truly deadly warriors.
Whenever the PCs level up and get access to higher-level followers, level up existing soldier to fill the new slots, and backfill with lower-level new recruits to fill the vacancies.
It won't change the balance of Leadership at all, but gives a more realistic feel and gives the appearance of rewarding the training they went through.
I think the first question we need is how you are running a 'war.' Training should match the system. For example if you are using the mass combat rules from ultimate campaign, training could represent knowing tactics. If you are using some other system, other advantages would probably be appropriate.
If you really aren't thinking of a 'war' but instead are just thinking of a extra characters in standard combat, and you wanted to give a bonus for training, I'd consider that training would give the warriors a PC level. Retraining a warrior into a fighter (although butchers/killing machines says slayer to me) using the standard retraining rules would take 5 days and cost 50 gp, which gives idea of how much 'effort' it should take a PC to accomplish that. This will make a warrior more powerful without increasing the level.
Teamwork feats?
They should also lose soldiers along the way due to this regimen. Some will desert, some will mentally break. And some will just die.
One thing I have done for my players in a similiar situation is just improve tactics and teamwork of the NPCs. For instance mass aid another against strong targets and archer focus fire. Other than that maybe allow them to define some premade formations/maneuvers and use them like animal tricks. Perhaps training allows them to increase their point buy, optimize their builds, or rr HP dice.