I think it'd be cool if the DLC fighters were from various other countries/factions. They could say they are mercenaries to make sense lore wise maybe lol
As far as a new faction, I think that MAY be a thing like a year from now, but I think it would take a HUGE patch to add a new faction.
My idea for new Heros:
Samurai:
- Female Hero. She has dual blades much like PeaceKeeper, but they are the same length. She can switch stance so the blades either become one, or she pulls out a longer blade. The dual blades have bleed attacks, the single blade does more damage. Both stances have different attacks/combos. She can throw one of her blades once during a duel, but will be severely limited after it is thrown. She will now only have 1 small blade and can't have the longer one. The thrown blade is unblockable and does bleed damage, but can be dodged.
Viking:
- A more modern Viking, a Spartan Viking halfbreed. Has that espada sword like in the movie 300. Has a unique parry that boosts attack by 10% for 5 seconds, executed like Warden's top guard light parry, but can do it for each guard. Can only get a light after this parry, no guard break. But has the normal universal parry as well. But he has a unique guard break that has the longest range in the game, he basically does a quick dash into guard break, so he can reach characters like Kensei and Nobushi after a parry.
Knight:
- A former Knight who deserted his army and became a pirate. He has a curved sword, with his attacke being as fast as PeaceKeepers. He has a unique parry as well that when executed, dashes behind the opponent for a unique back stab, or a free guard break on all characters.