Blighthawk was superman prior to 5.1, but has been overshadowed by Fluxfires since then. It's still very strong, but I'd expect further changes to Ghostly Bite before 5.2 goes live. See here for the latest from PTR
--they've put the cooldown back to 3 rounds, which almost certainly means it's going to get a damage nerf and/or the stun is going to be changed to something more punishing. Either that, or it's slipping through the cracks and Blighthawk will be worse than ever.
Also, if you like Blighthawk, try Ghostly Skull (spectral strike/ghostly bite) with Darkness.