The real question is what makes Disciple different from Melee.
In the original, there was no question about what unitcombat a swordsman, jet fighter, grenadier or curiasser was. Apart from the machine gunner...
But the difference between Melee and Disciple, or Archer and Arcane is harder to nail down.
Presumably Arcane units fight with spells and similar, not big ones like they cast once each turn, but lesser ones.
By the same token, Disciple units somehow use godlike powers to fight.
Kael made Paladins Disciple units because they use divine power when fighting.