You're right. I had no idea what I was doing in the last battle but it didn't really matter since it was so easy. Panchaea was simple because most of the bad guys were mindless idiots. On the bright side I finally had a reason to use the gas grenades. I also had all the good upgrades so there was no real need to level. The untouched LIMB shop was kind of ridiculous.
I am still not sure how to do Panchaea in a pacifist run for the trophy. You have to do the entire game without killing anyone (by your own hand) so I think I will have to stock up on every gas grenade I can find. As I have already seen all 4 endings I don't need to go for Sarif or the other chap so I can miss a few enemies there. There was a bit on a walkway where there were at least 20 of the nutters running at me. I managed to hide behind a couple of crates which they couldn't get past and headshot them all one by one but this obviously won't work if I am not allowed to kill any. I had the code for the final boss to turn off some of the security which made it stupidly easy. In the end I waited for the shield to go down whilst doing a lot of running around and then just used the typhoon once and it went down.
I suspect you could jump over them and make it to the other side of the bridge. I think there is a barrier there which they can't get past.