Shadowmourne...

"Weve had enough of the misinformed theroy that frostmourne would corupt you if you equiped it. "
"Arthas never had his soul stolen."
- amagais2

Is that so?

Muradin Bronzebeard: "Hold, lad. There's an inscription on the dais. It's a warning. It says, "Whomsoever takes up this blade shall wield power eternal. Just as the blade rends flesh, so must power scar the spirit." Oh, I should've known. The blade is cursed! Let's get the hell out of here!"
- Warcraft III: Reign of Chaos, Scourge of Lordaeron

Tichondrius: "The runeblade that you carry was forged by the Lich King and empowered to steal souls. Yours was the first one it claimed."
Arthas: "Then I'll make do without one. What is the Lich King's will?"
- Warcraft III: Reign of Chaos, Path of the Damned

Tichondrius seemed not to notice. He pointed to Frostmourne. “The runeblade you carry was
forged by my kind, long ago. The Lich King has empowered it to steal souls. Yours was the first one it
claimed.”
Emotions warred within Arthas. He stared at the blade. Tichondrius’s word choice had not
escaped him. Stolen. Had the Lich King asked for his soul in exchange for saving his people, Arthas
would have given it. But the Lich King had asked no such thing; he had simply taken it. And now it
was there, locked inside the glowing weapon, so close to Arthas that the prince—the king—could
almost, but not quite, touch it. And had Arthas even gotten what he had set out to get? Had his people
been saved?
- Arthas: Rise of the Lich King

Lady Jaina Proudmoore yells: "Stand back! Touch that blade and your soul will be scarred for all eternity!"
- World of Warcraft, Icecrown Citadel: Halls of Reflection

Lady Sylvanas Windrunner yells: "I dare not touch it. Stand back! Stand back!"
- World of Warcraft, Icecrown Citadel: Halls of Reflection

"An individual who wields Frostmourne will not part with it willingly. [The wielder] has its soul sucked into the sword. As long as the wielder's original body remains within 1 mile of Frostmourne, the sword maintains control of his body, and he may not be completely aware that his consciousness has shifted to the weapon. Beyond 1 mile, the sword cannot control the wielder's body, and the wielder of course finally becomes quite aware of his current state (if he is not already)."
- Warcraft RPG: Manual of Monsters

"You can't get Frostmourne because it would take control of your soul. Frostmourne would be playing your character, not you."
- Ghostcrawler, BlizzCon 2009: Raids & Dungeons Panel

"Now, Arthas has become so inseparable from his weapon that the sword's likeness has even found its way into the architecture of his fortress, Icecrown Citadel. Its hilt is never far from his hands; its ghostly whispers constantly ring in his ears. Frostmourne, as much as the Lich King, is the ruler of Northrend."
- World of Warcraft Community Site, Shadowmourne Preview

Shadowmourne is most likely going to have an item level greater than 277
Since the 25 heroic Icecrown Citadel drops 277 stuff...

The ilvl for it is 284. So Gigolas was right.