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.
Defeat Black Rabite.
Learn all abilities as any character.
Become a master swordsman.
Become a master magician.
Become a master cleric.
Play with all six main characters.
Complete Duran's story.
Complete Angela's story.
Complete Charlotte's story.
Defeat Mondoragon.
Learn 20 abilities as any character.
Accumulate at least 500,000 lucre.
Defeat Anise on hard.
Stop the end of the world.
Max out magic pot level.
Become a master fighter.
Become a master thief.
Become a master guard.
Complete Kevin's story.
Complete Hawkeye's story.
Complete Riesz's story.
Complete Chapter 6.
Defeat Archdemon.
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 chain ability from an unexpected acquaintance.
First time learning a companion's chain ability.
First time learning an ability.
First time planting a seed.
Obtain all achievements.
Defeat Dark Lich.