Huh, this seems interesting, I think I'll have a try at this myself.
So... I'll be using the Magic Item Creation-rules, right? I guess I'll be going with 3.5, because it's the one I've bee using since forever^^
Heck, I even had this idea which somewhat fits with freedom, even if it's idea is a bit... weird.
Spoiler: Acheron's Blade of Freedom
Acheron's Blade of Freedom
This katana appears to be made out of a pitch-black crystal and seems to be reacting to those with a powerful mind whenever they step close. Unlike any katana you've ever seen before, it's blade is jagged, sporting fine teeth like a handsaw.
Acheron's Blade of Freedom is a +1 Deep-Crystal Masterwork Bastard Sword. Like normal, the user can spet 2 Power Points to increase the damage dealt with a strike by +2d6, but in the hands of a Lawful Evil User, it reveals it's true power: Upon a hit, the target becomes subject to a Deja Vu-Power (ML 1, Will-Save DC 15 negates) and then Death Urge (ML 7, Will-Save DC 18 negates). Power Resistance applies.
Creation:22,026gp, 881XP, Craft Magic Arms and Armor, Craft Wonderous Item, Deja Vu, Death Urge
The servants of Acheron are everywhere. This is the story of one such warrior, a soldier of the Scourge of Battle, Hextor, with a name long lost to history. Back in his time, he fought with this very sword against the forces of Arborea. He stuck down many creatures of Good and Chaos, all having the desire to protect their freedom and trying their best to survive and defeat the marching forces of Acheron. All failed. And all contributed a small part of their essence, now forever locked inside the blade.
All except for one. Who it was, no one knows to this day. What is known is that the warrior was defeated on the battlefield and left alive to contemplate his actions. To erase the blame of his failure, he took his own life, disembowling himself, believing that he was strong enough to not loose their honor in pain without a second to behead him. This was his second failure, as he died with the shattered honor of a crying man.
The blade, however, resonated with something, as if it had felt that in this last moment, for it's master and those whose life they took, there was a final glee, a moment of peace.
Death means Freedom. Freedom you can grant yourself by throwing off the shackles of life. And this katana will guide you there and assist you and those you meet every step of the way to attaining it.
Right now, Acheron's Blade of Freedom has been cast onto Archon's second layer, frozen in stone. Waiting in a dream of blood. May the gods show mercy to the fools who wake it from it's slumber.
I hope I didn't calculate this wrong^^°
Not so sure on the whole use-activated business.