wtf are you talking about dark paladin doesn't say anything like that. it's a spellcaster. if it's in the gy you can special summon it with the effect. it's that simple.
to further clarify incase you wanna plead this further: "Must be fusion summoned" only means it can't be brought out of the extra deck with other card effects. when it's in the gy, it's fine.
No, it means the only way it can be Special Summoned is by Fusion Summon. It would say "must first be Special Summoned" if it worked the way you think it does. Go try it. (Or a similar card like Dark Eradicator Warlock if you can't afford Dark Paladin, which I suspect is the only reason you clearly haven't tried yourself.)
In Dark Paladin it clearly says "Must be fusion summoned and can't be special summoned by other ways" Is this card got revamped? if it is, So Amulet dragon can't revived Dark paladin from the graveyard