Full Iron and Diamond Tools

What if instead of wooden handles for tools we were able to craft iron or diamond handles.  Instead of using sticks we could craft iron or diamond "rods" first and then use them to craft the desired tool.  Iron rods would go with iron tools and diamond for diamond tools.  We could even use an iron handle on a diamond tool.  Since the tool would now be stronger it could last a bit longer when mining, however it would also be heavier so the hunger bar would run down a bit faster.