I know there isn't being actively discussed now, but I just had to comment as someone who raises Berners. I find it absolutely unbelievable that your breeder, assuming she is a reputable one, isn't discussing blue eye in Berners with you. It is very common and considered a fault for show purposes so it disqualifies them in the ring. I do not believe any breeder who says she has never had one, unless she has had less than 3 litters. I don't personally know a breeder who has never had a blue eye.
So onto the blue eye - there is absolutely nothing wrong with the functionality of the eye. It is simply a recessive trait - just like in us humans. It takes the gene in each parent to create it. Some Berners have one blue eye, and some even have two. The blue is typically a light, bright blue, just like the Aussie eye. If the pup is going to have a blue eye, you know it by 6 weeks of age. If a blue eye is there, it is not going to change.
If you are not going to show or breed the dog, and it will be a companion animal instead, there is absolutely nothing wrong with a blue eye in the Berner - it is unique after all.
I strongly encourage Berner owners to join the Berner-L or NaturalBerners discussion groups on Yahoo Groups. There is a lot about the breed that requires experience and knowledge, so these lists are very helpful.
Good luck