First, the attacks we're going to be working with:

GCDs:
Fast Blade - 160 Potency
Savage Blade - 210 Potency + enmity
Rage of Halone - 270 Potency + even more enmity
Riot Blade - 240 Potency + MP gain
Goring Blade - 250 Potency + 60 potency DoT for 21 seconds (670 potency altogether)
Royal Authority - 360 Potency
Total Eclipse - 110 Potency AoE around user
Holy Spirit - 430 Potency spell, adds 20 oath gauge points if you're in shield oath

oGCDs:
Spirits Within - 300 Potency (damage scales with remaining HP)
Circle of Scorn - 100 Potency AoE around user + 30 Potency DoT on each target for 15 seconds (250 Potency total per target hit)
Shield Swipe - 150 Potency + Pacify
Requiescat - 350 Potency (damage scales with remaining MP) + increases healing and damage magic potency by 20%, but only if MP is at 80% or higher
Sheltron - Blocks next attack and recovers MP. Costs 50 Oath gauge points.