Sanguine Reaper

School: transmutation [blood]
Level: sanguine sorcerer 4
Casting Time: 1 swift action
Components: V, S
Range: personal
Target: self
Duration: 1 round/level
Saving Throw: none
Spell Resistance: no
Description: You become affected by Sanguine Prosthesis and Sanguine Vulnerability. Additionally, you gain a stack of Bloodlust.
Note: You can possess no more than [x] stacks of Bloodlust at any given time.
[x] is equal to your caster level divided by two (rounded down)

Sanguine Prosthesis
Whenever a being (excluding yourself) takes damage from a bleed effect that you had inflicted upon them, you gain a stack of Bloodlust.
While you have at least one hand free, you can spend a free action in order to convert that hand into the form of a +1 dagger; you can spend a move action in order to revert your hand back to its normal form. While your hand is converted (via the effect of Sanguine Prosthesis), whenever you make a concentration check to cast a spell defensively, your check automatically succeeds.
Special: While you possess at least four stacks of Bloodlust, the weapon that you are wielding is treated as though it possessed the wounding special ability.

Sanguine Vulnerability
Whenever you sacrifice hitpoints via Blood Magic or Crimson Concentration, you gain a stack of Bloodlust.
Whenever you deal hitpoint damage (excluding bleed damage) to another being, you cause that being to become vulnerable to spells/abilities/etc. with the blood descriptor for [v] rounds.
[v] is equal to the number of stacks of Bloodlust that you possess