Here is the full list of all 20 Swords and Sorcery - there are Underworld - there are Definitive Edition achievements.
You've killed your first dragon!
You've tasted blood. There is no turning back.
You've won 20 battles and strike fear in the hearts of all.
You've defeated the final level of Highnest's arena.
You have rescued a child in dire need of help.
You have found your way into a vault, making it clear that none are safe from your wrath, wherever they may hide.
You've found your way through the Underworld to a neighboring town.
You've discovered a way to the true Underworld, into the Realm of Fire.
You found a way past the deepest of chasms.
You've seen the other side.
One of your spell casters has learned all of the known spells for his/her class.
A master bowman is in your ranks. All secrets of the trade are known to this companion.
You won 250 battles and are a force to be reckoned with the world throughout.
You've found one of the greatest treasure buried in the Underworld.
You've stopped a scourge from piercing through an ally's defenses.
You've inflicted your first critical strike to an enemy.
You've fought your first battle interrupting rest. Something you should be avoiding.
You have 50 entries in your bestiary.
Well, you've saved the world among a bunch of other things.
You've sounded the charge! Your companions bravely pressed forward.