Shock and traps goes through it, so it's not 100% god mode.
You are absolutely correct, It takes 2 other skills and a special enchanted weapon just to keep it up and its still able to be knocked out.
Anet obviously intended for it to be that long or they would have never reverted it in the first place, and when they did nerf it, they did not touch the duration. It's far from godmode!