Ok, so cqc from the front with these guys = not a good idea... point taken.
Yup, using a melee against these robotic fiends is not gonna work out so easy
Well I mean, it probably could look like a great, flawless idea on paper, right up until they turn you into dust at the last second, of course that is assuming their scattershots are as strong/stronger than when a player uses one, their reaction time (which considering how 343 acts regarding the knights, probably pretty fast) and how many times you need to jab them with an energy sword or shells froma shotgun before they cave in. On easy you could probably leeroy jenkins it pretty fine with your fist, but anything higher than that, I'll just let the krogan wannabes test that one.
Promethian + Scattershot= Target 4 every player on your co-op team.