Two tons is fine. I was thinking in terms of weaknesses that lifting objects would cause some sort of headache or something (if you wanted to be generic). You could also add the limit that she can't have her shield up [i]and[/i] lift objects (Or you can say that it activates). I'd also like to know how much the force field can take, because there's a [i]lot[/i] of force when you fall (Terminal velocity alone can hit harder than anything in this universe possible can).