Attack type : determines what defense your Drain Attacks will check when performed. Enemies have different resistances to different types. It will always be a physical type (Slash Pierce Crush).
Physical : the added value of both the base and the scaling.
Base : this damage is the flat damage of your Drain Attack, determined by the Blood Veil.
Scaling : this damage is going up or down based on how well your stats mesh with the scaling of the Blood Veil.
Blood, Fire, Ice, Lightning : if your Blood Veil is transformed, this is where you will see the added damage to your Drain Attack.
Drain Rating : determines how much Ichor you drain from an enemy with a drain attack. This value is used for the Drain Attacks only and not for regular attacks.