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.
Become a master guard.
Become a master swordsman.
Become a master magician.
Play with all six main characters.
Complete Duran's story.
Complete Angela's story.
Complete Riesz's story.
Defeat Mondoragon.
Accumulate at least 500,000 lucre.
Learn all abilities as any character.
Defeat Archdemon.
Learn 20 abilities as any character.
Obtain all achievements.
Purchase nitromyte for the listed price.
Defeat Black Rabite.
Stop the end of the world.
Defeat Anise on hard.
Become a master thief.
Become a master cleric.
Become a master fighter.
Max out magic pot level.
Complete Kevin's story.
Complete Charlotte's story.
Complete Hawkeye's story.
Complete Chapter 6.
Defeat Dark Lich.
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.
Open 100 treasure boxes.
First class switch.
Complete Chapter 1.
First cannon ride.
First encounter with Li'l Cactus.
First time learning an ability.
First time learning a chain ability from an unexpected acquaintance.
First time learning a companion's chain ability.
First time planting a seed.