A Paladin can get 3rd level spells from class level 11 with a high enough wisdom, but I'm not sure if the game has any 3rd level spells implemented (?) However, can the Paladin put 2nd level spells in the 3rd level slots that become available? Or do the 3rd level slots just not show up? Thanks
3rd and 4th level ranger and paladin spells show up with the 1st and 2nd level spells, there's a clearly visable warning in the descriptor box at the bottom, that says the spell will fail if put in a lower level spell slot.