Paladin or dark knight as dps?

If you want to be able to do decent damage as a tank class you'd have to pick warrior or dark knight. Paladin damage is just so much lower its not even worth attempting. Warrior can pull decent numbers if they gear towards it. Dark knights can get by but definitely not compete.

you can also try the dragoon. yeah, dragoons have a lance and not a sword, but they are DPS with heavy plate armor. kind of a medival knight, if you are looking for such a style.