Final Fantasy IV has plenty of moments that I remember fondly, but none of them rank as high as Cecil's battle with his dark half on the summit of Mount Ordeals. It's a symbolic fight where Cecil grapples with the evil deeds he performed as a Dark Knight, hoping to find redemption as a Paladin.

Accompanied by Porom, Palom, and Tellah, Cecil must climb the mountain to atone for his slaughter of the residents of Mysidia (depicted in the game's intro). By doing so, he can become a Paladin – a holy warrior that possesses the power required to defeat the villain Golbez. After a battle atop Mount Ordeals with the first of four elemental fiends, Cecil and company enter a mirrored room. Cecil is bathed in light and changes to Paladin form, but then must do battle with his Dark Knight reflection in the mirrors. In this fight, Cecil must let go of his aggression and take a defensive approach while the dark version continues attacking. After some cryptic dialogue that hints at later revelations, Cecil is victorious and becomes a true Paladin.

It's reminiscent of a sequence in the original Final Fantasy, where the heroes explore the similarly named Castle of Ordeals. In that case, they have to bring back a tail as a sign of courage, at which point Bahamut grants them improved character classes. The scenario in Final Fantasy IV also involves a transformation, but the story context surrounding it is what sets it apart. Instead of some dragon king randomly bestowing new powers, Cecil's class change is a significant step in his personal arc. 

Here's my sad confession: I always thought Cecil was better as a Dark Knight than a Paladin. But that doesn't make the moment any less important.