These new Demon Stock images are awesome. Great quality. You looks wonderful, the costume is perfect and the photographer seems to be very professional. (Amusing by the way, that when I read, when this was taken, it says Oct 2, 2034. You're way ahead of your time .)
Um...Hate to burst your bubble, but yeah. People do, or rather, did. Primarily in medieval Europe, when plate armor was popular.
See the tines there above the guard, where her left hand is? They're there precisely for this particular grip. It's used to get leverage when making a downward strike against a prone, armored foe. You need to have as much power behind the strike as you can get. Getting both hands around the heaviest part of the weapon, the guard, stabilizes the blade considerably so the tip doesn't slide across the armor (assuming it's plate armor), or break, or something else that would be considered "Not Good."