Didn’t Turalyon, the first paladin introduced in Warcraft 2, used a sword?
How did we turn into throwing magical hammers, spinning magical hammers, and hammer meteors?
Traditionally in real life, paladins are members of the knights of the round table, you rarely see medieval knights wielding hammers instead of swords.
In dungeons and dragons and other fantasy games, while paladins divine weapons can be hammers, it still tends to be a sword.
How did we go all in on Uther with his hammer wielding ways?
Maces and blunt weapons are usually better for fighting the Undead, as stabbing them with a sword or cutting off a limb won’t stop them, but crushing them into pieces will.
Maces are also better for fighting heavily-armored opponents as it allows one to collapse in the plate armor, since you likely won’t be able to stab through it.
Better question is when did paladins start doing damage from across the room? Conjuring up a giant sword from the earth seems like deep mage territory, to me.