A quick idea: Soul Edge and Soul Calibur as items

[Hypercat-Z]

This might sound crazy but what about having the two swords as items?
When they appear they have their original shape, but once grabbed they change into a weapon suitable for the character holding them. Plus or minus like the beam sword, but more advanced.

 

[Gene]

If we get a Namco character for smash 4 then I would be okay with this idea. Bowser or Ganondorf with the Soul Edge would be OP.

 

[Frostwraith]

while those look like interesting items, it will only happen if a SoulCalibur character makes in.

 

[grizby2]

weather or not a soul calibur character gets in, this is a very inspirational idea!

 

[Hypercat-Z]

while those look like interesting items, it will only happen if a SoulCalibur character makes in.

OBJECTION!
Lip Stick has been in the series since Melee without any of the protagonists of Panel De Pon being in the game, nor as character, nor as AT. So, the presence of a Soul Calibur char is not strictly necessary, since the swords alone are already more rappresentative of their game than the Lip Stick is of its game.
Thought, a Namco character or two are necessary to justify the presence of a not Nintendo object being in the game.
As for their difference, The Soul Edge is a double cut weapon. It cause a bigger damage than the Soul Calibur, and it also repristinate the energy of it's holder when hitting someone, but in absence of that it consumes slowly the energy of it's holder.