Here is the full list of all 44 Trials of Mana achievements. It takes around 50-60 hours to unlock all of the achievements on Windows.
Obtain all achievements.
Defeat Archdemon.
Learn all abilities as any character.
Become a master fighter.
Become a master thief.
Become a master cleric.
Accumulate at least 500,000 lucre.
Play with all six main characters.
Complete Kevin's story.
Complete Charlotte's story.
Complete Hawkeye's story.
Defeat Dark Lich.
Learn 20 abilities as any character.
Max out magic pot level.
Defeat Black Rabite.
Stop the end of the world.
Defeat Anise on hard.
Become a master guard.
Become a master swordsman.
Become a master magician.
Complete Duran's story.
Complete Angela's story.
Complete Riesz's story.
Complete Chapter 6.
Defeat Mondoragon.
Find Li'l Cactus in all possible areas.
Accumulate at least 100,000 lucre.
Complete Chapter 5.
Open 200 treasure boxes.
Complete Chapter 4.
First ride on Flammie.
Complete Chapter 3.
Complete Chapter 2.
First ride on Vuscav.
First class switch.
Open 100 treasure boxes.
Complete Chapter 1.
First cannon ride.
Purchase nitromyte for the listed price.
First encounter with Li'l Cactus.
First time learning a companion's chain ability.
First time learning a chain ability from an unexpected acquaintance.
First time learning an ability.
First time planting a seed.