If anything gets nerfherded to death for Nocturne, and sorry if I'm a little late to the show - but - all that needs to really be nerfed in the case of Nocturne's abilities is the range of Unspeakable Horror; it gives him a really high advantage against enemy melee and even ranged champions who don't have a fear or stun of their own to lob off.
And despite his only Dodge item being Ninja Tabi, a well-played Jax can wallop that little would-be-boogeyman pretty well, as long as one uses Counterstrike at every opportunity before Nocturne fears. Even then, just a teeny nerf on the range of it wouldn't hurt too much, and give a tiny bit more of a chance of escape, if at all.