Here is the full list of all 38 Souldiers achievements.
Defeat Iktala on Soldier or Warrior mode.
Defeat Babylon on Soldier or Warrior mode.
Defeat Birk on Soldier or Warrior mode.
Defeat Project S on Soldier or Warrior mode.
Defeat Agginox on Soldier or Warrior mode.
Defeat all Dark Warriors.
Defeat Ratatosk on Soldier or Warrior mode.
Defeat the Minotaur
Defeat Brigard.
Defeat Sangrigor.
Defeat all Royal Scorpions.
Defeat Galath a second time.
Defeat 5,000 enemies.
Collect all Dark Crystals.
Defeat Beigon on Soldier or Warrior mode.
Complete the game as an Archer.
Collect all orbs in the game.
Defeat 50 enemies using secondary weapons.
Destroy 3,000 environmental objects.
Discover 50 hidden rooms.
Upgrade your protection the highest level.
Upgrade your weapon to the highest level.
Inflict altered states on your enemies 50 times.
Use 100 potions.
Defeat 1,000 enemies.
Be revived by the Valkyries after falling in combat.
Destroy 10,000 environmental objects.
Find all of the hidden rooms.
Complete the game as a Scout.
Complete the game as a Caster.
Complete the game as all three classes.
Unlock all skills.
Complete all side quests.
Collect all secondary weapons.
Reveal 100% of every map.
Complete the Bestiary in your Encyclopaedia.
Complete the game on Warrior mode.
Finish a game on Game+ mode.