Hello,
The blood mage has the shortest attack cooldown of any hero in wc3 when looked in the editor (for people unaware of what it is, the value is different for every hero and determines their base attack speed to which agility and other attack speed buffs are then added), which is 1.64.
However, this value seems to be interpreted as 2.0 by the engine (can be verified easily by creating a custom Blood Mage with 2.0 attack cooldown, the attack speed does match).
1.63 and 1.65 both work properly as attack cooldown values and give the blood mage a much better attack rate.
So the blood mage is currently dealing 22 percent less dps than it should.
Probably not a major discovery but since I found it I am sharing it here.