Anti-Climax Boss: All the final bosses except Gades turn into this if you use Mirror because Amon, Daos and Guard Daos only use magic meaning Mirror will reflect everything they use.
Awesome Music: The normal battle theme. Most SNES JRPG normal battle themes tend to be slower, more uneventful, but this game's normal battle theme is a lot more upbeat which makes normal battles a lot less boring when the theme playing in the background is so nice.
Complete Monster: Daos, when his sister, Erim, is revealed to have been living as a human, mentally assaults her, mocking her desire to live as a human.
Game Breaker: The Mirror spell, learned by Jerin at level 32, will reflect any magic thrown at you by the enemy, but will let healing and buffs through. Using Mirror on everyone makes the final boss battles jokes.
Good Bad Bugs: If the Hero is dead going into the fight with Artea's apprentice, you will start the fight with no HP, but still able to fight. However if you take a hit, you die because the game has to register that you're at 0 HP.
Guide Dang It: The manual doesn't explain the intricacies of the game's Combatant Cooldown System, and no-one, not even the FAQ writers, really knows exactly how equipment Weight works. Also, while you can look at a spell's description by pressing the X button, there are no item descriptions for consumables or equipment, so you have no idea what they actually do.
Narm: Guy proclaiming that he's "Over 100 years old and still kicking!" only to walk ten feet and keel over is perhaps a little funnier than it should've been.
Instead of being able to target individual enemies, players have to target groups of enemies instead, and the party will just attack enemies within that group at random. This makes Wolf Pack Bosses far harder than they need to be.
If a party member is set to attack a group and that group is wiped out before their turn comes, they'll just swing at the empty air and waste their turn.
Tear Jerker: If one plays this after the second game anyway...
That One Boss: The quartet of Demon Lords and the trio of Goblins that are fought early in the game. If the player were able to target individual enemies (see Scrappy Mechanic) then they'd both be relative pushovers, but because you can't they're two of the hardest boss fights in the game.
The Phantasm in the Ghost Cave can prove quite a difficult stumbling block. He's almost immune to magic damage after casting Shield on himself, regularly casts confusion and sleep spells on your entire party, and spams Spark, which hits your entire party (particularly the low-MGR Aguro) for a considerable chunk of damage.