How to lower attackspeed

One of the weapons in my map shall lower the wearers attackspeed. I could do it with triggers and stuff but isn't there an easier way to lower attackspeed (like basing it on an ability)?

Well, theoretically, you could alter an Increase Attack Speed item ability and give it a negative value. Although I've never tried it.

ahhhh... nevermind I found it out myself ^_^