So... according to this thread, anything that affects melee attacks can affect the Whirling Blade spell.
How does it work with Blade of Blood? Only the first creature struck is affected?
Correct. After the first hit the spell is discharged.
What about Bladeweave? Apply normally against all targets?
Bladeweave specifies that it works once per round. If you attack 10 guys in the line, you could have the bladeweave affect any
one of them that you successfully struck.
Arcane Strike and Power [Attack] could work too...
It appears they should.