That is an excellent cosplay, you've got the look down pat. I love the pose and the expression, especially the eyes. Those are the things that really make a cosplay. You could have a perfect reproduction outfit, but it's not worth a darn if you just aren't trying.
WOW. Kinda creepy but sexy in a weird way. :3 And inaccuracy can happen to all of us. Your Bellatrix came out lovely, as well as you capturing her more... psychotic tendencies with just one expression!
As an avid Harry Potter fan, and a deviant who doesn't really comment or critique often, I love your cosplay, Elder Wand or not. You did an amazing job on it, and you clearly put a lot of time and effort into it. I admire your courage a lot, so don't let anyone get you down =].