Dark Knight will just have a sword (longsword, not greatsword) and no shield I bet. Possibly two hand the sword to go for that iconic Cecil DRK stance that Sephiroth later used.
I wouldn't mind seeing an offensive shield user. Give them some crazy looking spiked shields or something with some shield slam attacks, could be neat.
I did 3v3 arenas in WoW at different times with a prot warrior and prot pally and always liked the shield based attacks, so I'd love to see something like that be an actual DPS class.