Again this wouldn't promote long distance fighting just longer ability to hold a army in the field,
Which equates to long-distance fighting. Whether or not *you* would use it for that, that's what it would be used for. Anything that allows you to stay in the field longer means that you can march farther with that longer time.
Now even with this system a realm can't march across a continent to wage war on another realm having to cross 5 realms in the process simply due to the fact even with a smith by the time they got there they have gathered way more damage than the smith could fix making them still vulnerable to any attack. It would allow them to simply stay in the field and remain ballsy longer before having to go back for refits.
Your argument isn't making sense to me here. You say that this won't let you march farther, because the damage it can repair is so limited. But if it can't repair damage from marching enough to let you march farther, then how can it repair damage from doing... anything else? Damage is damage. It's not like marching damage is different than sitting around damage, which is different than battle damage. So how does your system let you repair enough damage to stay in the field longer, but not let you repair enough damage to march farther?
