Question How would a go about adding effects or particles to an animation?

The title says the most
I'm making an attack animation and the attack is basically instant, how would I go about adding custom effects into the animation ie. a line that shows the weapon's path

 

Is this not possible in unity's animator?

 

One way of doing this, is you might have to attach the particle emitter, to a bone specifically put into the characters hand or in the characters weapon, that is used to attach things to it. I hope I understood your question correctly.