Here is the full list of all 19 Symphony of War: The Nephilim Saga achievements.
Defeat all enemies in Chapter 12.
Defeat Beatrix in Chapter 11.
Complete the main story on Captain difficulty.
Complete the main story on Warlord difficulty.
Have 9 Units in one Squad.
Unlock all Techs in a single playthrough.
Reach Max Faction Rank.
Surrender all the Imperial Squads in Chapter 27.
Army size reaches 150 Units.
Surrender 200 enemy Units in a single playthrough.
Reach Faction Rank 9.
Rescue all 4 children in Chapter 15.
Use a Proof of Merit on a Unit.
Form a Bond relationship.
Class change to Tier 3.
Hire a Unique Mercenary.
Find or purchase an Artifact of Legendary rarity.
Reach Faction Rank 4.
Class change to Tier 2.