From blood spatter you can determine the angle and the velocity of the blood. If there are several drops, you can pinpoint the source of the blood. Knowing the distance from the source to the blood spatter and the velocity can let you know the height and estimate the force applied.
This all will able you to determine:
1. The angle of impact for a drop of blood
2. Point of convergence for several drops of blood
3. Distance to the point of convergence and a blood drop
4. Point of origin, the source of blood