Here is the full list of all 11 Unsung Warriors - there are Prologue achievements.
Collect 500 gold.
Drop a box on an enemy
Find the Cavern of Names inside the crypt.
Destroy an enemy with a bomb.
Defeat the skeleton boss.
Destroy the skeleton boss by using only your fists as a weapon.
Destroy an enemy with an oil lamp.
Destroy an enemy by stabbing him in the back.
Save the lost brother from the crypt.
Destroy an enemy by pushing him under a crushing block.
Destroy an enemy by smashing him into spikes.