She didn't learn anything...
Spoilers.
Towards the end of the film, Ellis suffers unjustified treatment at the hands of the barbaric victors who accuse her of being a collaborator. She's beaten, sexually assaulted, covered in excrement. After she escapes this, she's almost murdered by Gerben* for the death of his son, when the fact is she risked her life to save him. Ellis knows better than anyone everything that's wrong about the notion of revenge.
And yet, when she gets the chance to murder someone in revenge she takes it eagerly. I was surprised - I thought the film would end with her opening the coffin, handing Hans over. Sadly, she hasn't learnt from her experiences. She's just as bad as everybody else.
*OK he never gets close, but he would have killed her given the chance