Okay, the only thing I am qualified to answer is the Siegfriend Schtauffen vs Arthas Menethil question.
First, we need to decide WHICH versions are going to fight each other. If weâre discussing Arthas pre-Frostmourne (living and blonde) against Siegfried (also living and blonde, but without Soul Calibur) then I think Arthas would win. The Light can be used to empower himself, while all Siegfried can do is meele and charge.
If we choose to go Siegfried with Soul Calibur vs Arthas (pretty and blonde) with Frostmourne, then I would give the fight to Siegfried. Soul Calibur can augment its user extremely well, and if we use its powers from SC IV then we have a weapon that can overpower Frostmourne, which in Arthasâ hands at current is just a really good cursed blade.
Takes a shot of Red Bull Now we come to the penultimate confrontation: Nightmare (Siegfried host) vs Arthas (Death Knight). This battle would be another loss for Arthas, as Soul Edge trumps Frostmourne in terms of power level. Frostmourne is, again, a really good weapon. But Soul Edge can create fissures, burst into flames, and has an impressive reach of three anime protagonists from the 90s.
And now, for the ULTIMATE BATTLE: Nightmare (no Siegfried/Possible Night Terror) vs Arthas (Lich King). This one is going to be tough to decide, as Arthas and Nightmare are both overpowered in this scenario, and neither can break their weapons as both are evil blades (Soul Edge can only be destroyed by Soul Calibur and Frostmourne was destroyed by a holy weapon, the Ashbringer)
Frostmourne and Arthas are inseparable, and the blade heightens his already formidable powers that have merged with Nerâzhul. His command of necromancy and just augmented power in general would give him an edge.
Nightmare, however, is faster and less prone to questioning himself. This is when Soul Edge inhabits just the armor and has no host to hold it back from its full, vengeful glory. He can tap directly into the powers of Night Terror and heighten his brutality up to an eleven. Not to mention he still has access to fire and explosive magics conjured from the sword, which will continue to prolong the battle unless destroyedâwhich Frostmourne cannot do.
In the end? Iâd have to give the wins to Siegfried/Nightmare. The world they come from is far more âpowerfulâ when it comes to their weapons of choice. Arthas is OP, but Soul Edge transcends history and the world.