Neutronium blade fills that role pretty well. It will never break.
And the large one has 160% efficiency. But you need 72 neutronium for it, that are 1152 naquadria and americium, you need 1.223.059.046.400 EU and it takes 7.2 days to produce it, as well as 10000 seconds per double plate in the bending machine. As if anybody has the time to do that.