Since I am far too lazy to parse any of this my basis comes off of melees that dont crit nuke naturally (warriors, monks, pets). I typically play enc/wiz so naturally blades is up at all times. My indicator that this AA is working properly would have been to see at least one or two crits go off; so far, nothing.
Edit: I also grouped with a beastlord a few times that had no crit AA's. No dice on that one either.