Rey had to have some help in that final lightsaber battle against Ren. It either came from Luke or Anakin. I mean she went from zero to 60 with her force abilities.
Well I do think it will shown in Ep 8 that she had previous training in the force. Also you don't need to be a jedi/force user to use a lightsaber and she had shown the ability to take care of herself with that staff. And Kylo was hurt pretty badly. Chewys crossbow was shown several times (for this reason) to have blown **** up and he took it straight to the stomach.