Actually, gravity is the weakest of the 4 fundamental interactions (below electromagnetism, weak interaction and strong interaction), yet it has astronomical range.
I think her ability isn't related to gravity (in order to change it, her mAss would have to change, or she would need a lot of energy -- e=mc2), but to pressure (=force/area).
In other news, I have read the raws to the end, yet I'm still anxious and hyped.

No one can beat gravitation and her ass is made of gravitation. :P

50 tons her ass, more like.

50t my ass.

what