1.) All hits that land do a minimum of 3 damage, unless the defender has the untouchable skill, in which case "No Damage!" becomes possible. Untouchable is a class skill of heavy infantry (Knights, Generals, Barons, etc.) plus the main character.
2.) Infantry units may elect to sprint, gaining +2 movement at the cost of being afflicted with 2 turns of the "fatigued" condition after movement or combat. (The condition counter globally increments down at the beginning of enemy phase, so the condition actually lasts for the subsequent enemy and player phase).
Fatigued halves the unit's STR, DEF, MAG, RES, SPD & SKL.
Units may sprint while fatigued, but they reset the 2 Turn fatigue by doing so. This way infantry can indefinitely match their mounted peers MOV but will also be indefinitely crippled in combat.
If capturing/rescuing exists the unit can't spring while having a held unit.
3.) Many varieties of HP, each with separate growth rates, boosters, etc, some being enemy only. This is their priority, from lowest to highest. A unit dies when their lowest priority health is > 0.
Green Health is vitality, reduced by DEF/RES depending on whether the damage is physical, magical or hybrid (the average of the two stats).
The boring vanilla Fire Emblem HP that the vast majority of units have.
Yellow Health is fortune, ignoring damage type and instead uses LCK as the damage-reducing stat.
Gray Health is overheal, available aplenty but treated as if having 0 DEF/RES.
If [overheal < Attacker's ATK], defender's overheal = 0 & defender's next health bar is subtracted by [ATK - [DEF/RES/LCK + overheal].
Dark Red, Dark Blue and Purple Health are "barriers".
If [barrier < Attacker's ATK], defender's barrier = 0 & defender is inflicted with the "enfeebled" condition. Excess damage is NOT dealt to lower priority.
Enfeebled negates all defender's skills & authority
Magical damage skips Dark Red for the next health bar, Physical skips Dark Blue for the next health bar, and Purple cannot be bypassed.
Orange Health, like Green Health, is reduced depending on damage type, but it sets itself to 0 if defender is hit by a crit
Might be fun for a gimmicky paralogue: put a bunch of enemies with only Dark Gray Health and plenty of it.