Decreasing Attack Speed

Anyone have a preferred method of slowing unit attack speed without: a) using a spell, b) and without also slowing its movement?

What I'm doing right now is not very efficient.

Change the attack cooldown

Well... you can just edit the slow spell to not slow down movement. But if its just a single units attack speed, the unit editor works great.

I suppose I should rephrase to clear up what I meant. I have a trigger that, when active, is supposed to decrease the attack speed of a specific unit. I know about cooldown, but unfortunately there is no trigger to decrease it in game. As for modding a spell, it is a possibility, but I would prefer not to do that unless I have no other option.

What I am doing right now is:
Set unit animation speed = animation speed (var) - X %.
I then reference the unit into an array and, depending on what its speed is, I add a percentage of it's damage back to the attacked unit's life.

Just looking for a simplier way through triggers.

Make a unit just like it but with a longer cooldown. That always works.

Thanks Electro, but what I'm looking for probably isn't efficient or possible with just normal triggers (since I want constant decreases, rather than one-shots). I thought of a different method though, that doesn't require attack speed changing, so I'll use that in it's place.