Overall lifetime Stats should be added for individual soldiers, stats like Kills, Deaths, Number of Battles, Repairs, Structures Built, Soldiers Revived/Healed, Longest Kill or Most Mills or Artillery Kills or Tanks/Aircraft destroyed in a game and different streaks n etc. , having their own kill to death ratio too, so all those stats they earn in battle don’t disappear after the battle. The stats and experience of the soldier should effect their skills and how they perform in battle like the soldier with most experience/stats would earn more XP and maybe even boost skills/performance of their squad members acting as a Leader Effect but only while they are still alive in battle. Depending on how impressive their stats are or certain statistical achievements achieved like higher kill to death ratio or points captured they should earn medals for them like Medal of Honor or Iron Cross n etc. depending on the achievement respective of their nation and the medal should show up beside their name and on their uniform.
This way your soldiers won’t be that expandable and you will think twice before removing them or sending them to reserve so easily making them more valuable to you depending on how long you have fought with them, also you will think twice before using them as cannon fodder in battle as it might effect their stats and kill to death ratio. Currently if a soldier reaches level 5 rank they all pretty much became the same as every other soldier and this will distinguish them from other soldiers and become more then that level 5 rank.
—Side Request maybe also add individual traits for soldiers to give them personality to determine if they have traits that make them brave or cowardly or selfish or zealous, if they are cowardly they will retreat and run away from overwhelming enemies while defending and hesitate to charge an area or building with lots of enemies and if they are selfish they will be less likely to throw grenades away to save other teammates and only save one self…If they are brave they will not hesitate to attack the enemy and if they are zealous will fight till death more and selfless will maybe even throw themselves on grenades and more likely to heal and revive others under fire if they are medics, their experience and stats would determine the traits.
But this addition might need concept of retreating for AI soldiers to be added in game who will retreat back to spawn points or to previous or closest holding point or even closer to other teammates if they face significant enemies attacking them or if they are attacking objective which has too many enemies or facing a lot of enemy fire, would eventually stop following orders and run, cowardly traits should also make soldier cower more in cover if suppressed with fire then to shoot back. Retreating concept would be more dependent on their traits of what they are more likely to do.