So if I'm doing this right, a little tired so my math might be off.
Dark Veritas:
Base Attack (Potted): 180 attack
Odin: 60 attack
Passives: 20% Attack, Large Sword Mastery (50%), Darklord (30% w/heavy armor, 75% DH)
Equipment:
Weapon: Sword of Loto (125 attack)
Helmet: Prishe's Hairpin (45 Attack)
Armor: Iron Colossus (15 Attack)
Accessory 1: Martial Gloves (40 attack, 50% TDH)
Accessory 2: Desch's Earring (45 Attack)
Materia 1: Buster Form (100% TDH)
Materia 2: Buster Form (100% TDH)
Materia 3: Sworn Six's Pride - Dark (30% w/heavy armor, 30% w/large sword)
Materia 4: Sworn Six's Pride - Dark (30% w/heavy armor, 30% w/large sword)
(180 + (180*2.2)) + (270+(270*3)) + 60 = 1716
That should be his attack based off that. His weapon will change his final attack number a bit. Excalibur II from Steiner will increase his attack by another 20 and give him Light Element to work with Orlandu. You can equip Glauca's Sword for the same attack but guaranteed dark element. Save The Queen from Beatrix is another option that gives him another 40 attack and is neutral element. If you have Dandelga or Karyuo (both Limited Time units) he can do Fire as well. Dark Edge already has Dark Imbue so it's better to go with something other than Glauca's Sword though.
I also only used Odin which is 60 attack. 3-star Ifrit is closer to 80 attack and can increase his base attack even more with the skill that increases the benefit a character gets from equipping the Esper. It's not as good as the Killers but if we're able to increase the SP of an Esper in the future, this should change. Also, I didn't take into account Friend stat bonus either.
So when you look at this with his 900%/1200% potential on Dark Edge and the fact he has 75% Killer on Beast/Dragon/Human on it as well, it's pretty clear why they didn't want to give him 75% TDH on Darklord
