I doctored a friends el-cheapo axe with fiberfix just under the head. I did a cord wrap just for aesthetics but I don't see why the fiberfix wouldn't work by itself. I've never tried splitting with it though so I don't know how it holds up to impacts.
My dad, a frugal fellow if ever there was one, uses squares cut from a pair of old neoprene waders held on with electrical tape as his over-strike guard of preference.