Does Blade Arc use Attack or Caster Speed?

I’d like to try a Blade Arc Commando. Assuming I don’t use the Clean Sweep transmute, will I need to stack Attack Speed or Caster Speed (please let it be Attack).

I’m pretty sure it’s attack speed.
AFAIK any spell where your character’s weapon is coming in contact with the target scales off of attack speed.

Forcewave (when used with Tremor) is the reason, why you often see 2 handed melee weapons with cast speed.

What about “Phantasmal Blades” which one use?

Cast Speed.

Phantasmal blades, wrath of agrivix and phantasmal blades use cast speed despite having % weapon damage

Thanks for the information.