I've stripped brake hose nuts with flarenut wrenches before. I now use a pair of Irwin 4LW vise grips instead:

https://www.amazon.com/gp/product/B00004SBBE/ref=oh_aui_search_detailpage?ie=UTF8&psc=1





Sometimes the flarenut wrenches will flex because it's not entirely closed (you are missing one of the six sides) and a way around that is to just vise grip the wrench like so: