In games like Spellsword and War of Emperium, the spell's wraiths and guardians attack faster than regular
I'm just wondering how this is done, because it takes the units to attack much faster than regular
Let me have a guess....disabled sprites?

There is no way, to my knowledge, to actually make the units attack faster, most likely they are removed then recreated in order to get rid of their cooldown.

Alright then, I'll do that.

They are most likely given attack orders when spawned, where as regulary spawning them they would have to register that there is an enemy then attack. Try creating and ordering them to attack.