This powerful and ancient weapon, made entirely of Moonsilver, reflects the very nature of Luna herself. It is a bizarrely-shaped mass of curving metal, with edges, grips, and guards in unexpected places, and never the same twice. At any point in time, the sum of its bonuses to accuracy, damage, and defense plus one-third of its bonus to initiative must sum to twelve. Its wielder may reflexively adjust those bonuses at any point, shifting up to a number of bonuses equal to her permanent Essence each round (with three points of weapon speed equal to a single bonus point). None of the Flowing Blade's bonuses may ever be shifted below zero.
Example: Hunts Without Sound is a Full Moon Lunar with permanent Essence 4. At the beginning of the round of combat, the Flowing Blade is Speed +6, Accuracy +3, Damage +4L, Defense +3. (6/3+3+4+3=12) She gains the initiative and decides to split her action three ways for two attacks and a parry. Before attacking, she converts the Speed +6 into Accuracy +2 (two shifts, leaving her with two more this round), so the weapon is now Speed +0, Accuracy +5, Damage +4L, Defense +3. She then performs her two attacks. Her opponent, an Earth-aspected Immaculate Monk, survives and then attacks her. Before using her parry, she uses her other two shifts to convert a point each of Accuracy and Damage into Defense, so it is now Speed +0, Accuracy +4, Damage +3L, Defense +5. The next round, she barely loses initiative, so she shifts one point of Defense into three of Speed, taking the lead, and then puts three more points of defense into Damage, making it Speed +3, Accuracy +4, Damage +6L, Defense +1, allowing her to deal a killing blow to her foe.
The Flowing Blade does not receive any additional magical material bonus beyond its wondrous adaptable nature, and can only be attuned to by Lunar Exalted, as only their auras are flexible enough to harmonize with the blade's. It requires a commitment of 8 motes of Essence, and has two settings for hearthstones that ride along the surface of its changing mass.