Armistice is da bomb, it's an ulti with range, so you can affect let's say all of his fleets but only half of the structures in the gravity well, so all you need to do is to sent in another fleet and destroy the unaffected structures for a good 30 to 60 seconds.
Plus it doesn't affect culture bonus right? So that's 60 seconds of anti matter recharge for the TEC, if you are under your culture.
You can pretty much solo your Akkan into a system, embargo and bomb the planet, Armistice the coming fleet and sent in your main with Kol or just get away for nothing. Armistice is a god power.