While technically there are weapons/gear which are again technically higher tier variants of weapons/gear available before, better is heavily subjective and it is unlikely that there are or will be weapons which are literally reskinned beefed up versions of the same weapons before them, in this case the Curved Sword.
Edit: As Sumgai points out/says, the design philosophy for gear is that they can still be as valid/viable an option at level 10 as level 5, etc. While some weapons might be more optimal in context to builds, that is more relative than anything.