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