Blood Bone Staff

Weapon The Bone carries the memories of many different weapons that it owner once wielded which can be conjured forth with an offering of blood.
  Base Form
Quarterstaff | 1d6 bludgeoning | Versatile (1d8), Blood Transformation
Blood Transformation: This weapon can be transformed into a different state either by sacrificing 1d6 of the wielder's hit points or by either killing or reducing a creature to bloodied.
Alternate Forms
Spear | 1d6+1 piercing | Thrown (20/60), Versatile (1d8) Glaive | 1d10+1 slashing | Heavy, reach, Two-handed Pike | 1d10 + 1 piercing | Heavy, reach, Two-handed Sythe | 2d4+1 slashing | Two-handed, Cleave Lajatang | 1d8+1 slashing | Finesse, Monk weapon, Vaulting strike
Uncommon

A 6-foot long bone from the wing of a twisted Kenku Aberration. It is exceptionally light but sturdy and emits a disturbing warmth that pulses steadily. When touched with bare skin it feels slightly sticky; as though it is trying to suck the blood from your body.
The Lajatang is a lightweight weapon similar to a glaive with small blades on both ends. It can be used to make rapid spinning slashes and to make vaulting leaps. Difficult to wield properly, but especially deadly in the hands of a monk.