It's really rough to give a solid average, considering how much variance there is in content these days. Optimal gear set should look something like this:
ItemSet 226691
Mekira-oto +1 is better on WS bonus days and most of us use Soil gorget/belt just to save space with other WSs. Other small things like Fracas Grenade being better with LR up on most targets, Rajas Ring being swapped out for Pyrosoul/Strigoi depending on your STP needs, grip depending on STP etc.
99 Apoc Catastrophe is usually worth using full-time over Entropy, save if you need to fill your MP in an emergency.
There are many Apoc haters around, but it is still a solid weapon and
definitely worth taking to 99. Yes, great sword is better in many situations but 99 Apoc is an amazing weapon that any serious DRK should have in their arsenal. Pre-congratulations on your Apocalypse!
Small personal FFXI life lesson: Never sell gear to finish a relic faster. It's most likely never going to be worth it in the long run.