Caliburn has the hax +10 crit.
...which might not matter for melee.
Broadswords already sport a crazy crit stat. I use a Goddess Caliburn 222 braodsword and a Giant 222 Broadsword (which will become Goddess Caliburn soon) and I have some pretty crazy crit with Goddess Title and stiff cap (around 75% - 80% untransed).
But in order of more damage it goes Horn > Spike > Obsidian > Caliburn for suffix and Goddess is the only one I know that is a worthy prefix (especially in Broadswords low repair rate case)