Knightmare mode is EXCEEDINGLY HARD! What you're failing to take into consideration is that the thugs cause more damage and you get no warning on the HUD above the heads, so you never know who's going to attack or who's going to rush you. I'm on Knightmare mode and ready to quit--specifically because of the first airship part where you have to rescue Stagg. You have to defeat 26 thugs (one with blades). You're allowed 4 or 5 taps from the thugs and then you're dead. Your freeze bombs are useless. Your batarang does no damage. The electrical charge helps a little, but you're constantly swarmed by all the thugs. They don't wait their turn like they do on the first playthrough, they all attack simultaneously. The closest I've come fighting this battle for 4 hours is to get down to 4 thugs before dying. So yeah, it's an almost impossible playthrough, and I'm not going to waste anymore time trying to beat it.