The switch from bronze to iron was not driven by iron being better (Iron Age I tools are slightly worse than Late Bronze Age tools) but by the collapse of international trading - it was too hard to get both tin and copper into the same place to make good bronze anymore. Bronze blades, made by someone who knows what they're doing (in casting, hardening, and finishing) can be quite good. They will not be competitive with modern steels, though. A precise answer to this question requires you to define what you mean by "good blade". Steel will be harder, more wear resistant, less brittle, tougher, etc. While I would love to have one of Neil Burridge's bronze age replica swords, I'd be pretty unhappy about replacing any of my pocket knife blades with bronze.