引用元:
Satarn
Aside from the fact that most people just check on fflogs(damage taken section has a list of all attacks which are color-coded for physical, magic and dots), you can also just look at the battle log in-game. There's 4 types of different log messages based on whether the attack is physical instant, physical cast, magical instant or magical cast:
EnemyName uses AttackName. - physical instant
EnemyName readies AttackName. - physical cast
EnemyName casts AttackName. - magical instant
EnemyName begins casting AttackName. - magical cast.
Would it be nice if there was some easier way to see it mid-combat, like colors or something? Yeah, totally. However saying there's no way to tell in-game is completely incorrect.