Here is the full list of all 28 Aggelos achievements.
Finished the earth temple
Used your first herb
Reached level 2
Reached level 10
Reached level 20
Accumulated 100,000G
Finished the water temple
The power of fire is yours!
Finished the air temple
Finished the Fira event
Gave the pendant to the princess
Played a lyre in the pub
Overcame the world of shadow
Defeated the evil mouse in the castle basement
Found the angel feather
Defeated Valion
Defeated the Dark Lord
Found the sword of Aggelos
Found the armor of Aggelos
Blessed the armor of Aggelos
Collected all equipment
Collected all scrolls
Collected max hearts
Collected max MP
Finished the game at or below level 15
Achieve 100% completion with no deaths
Passed the flying dinosaur test
Beat game on hard mode