For an HNM shell, G-horn is broken. For melee, Amanomurakumo seems to outshine the rest (Sorry you Apoc. DRK's, but it's just not that impressive to me).
The worst however... I'd have to say Claustrum. That is the biggest waste of gil I've ever seen put into a relic. The worst for an actual melee job though, I'm going to hand off to Guttler. I've seen one stage 4 axe the entire time I've been playing. No stage 5's. Wonder why that is?