Final Build:*
(4) Supreme Essence of Might: 139 Might, 17 Vitality
(1) Greater Essence of Might: 139 Might
(1) Supreme Essence of Vitality: 139 Vitality, 17 Fate
(4) Greater Essence of Vitality: 139 Vitality
(2) Supreme Essence of Fate: 139 Fate, 17 Vitality
(1) Greater Essence of Fate: 139 Fate
(1) Greater Essence of Finesse: 3749 Finesse
(1) Major Essence of Finesse: 3280 Finesse
(1) Supreme Essence of Critical Rating: 1229 Critical Rating, 386 Critical Defense
(1) Greater Essence of Critical Rating: 1229 Critical Rating
(1) Greater Essence of Morale: 875 Morale
(1) Minor Essence of Morale: 746 Morale
(1) Major Essence of Critical Defense: 2702 Critical Defense
(5) Base Might (one on each slotted armor piece): 119 Might
(1) Greater Valorous Leggings of Penetration: 239 Might, 205 Vitality, 768 Critical Rating, 614 Physical Mastery

Total stats:
Might: 1290
Vitality: 1019
Fate: 434
Raw Morale (from morale essences): 1621
Finesse: 7029
Critical Defense: 2702
Raw Critical Rating: 2458
Raw Physical Mastery: 614
Total Morale (1621 from raw morale essences + 3057 morale derived from vitality essences/leggings): 4678
Total Critical Rating (2458 raw crit rating essences + 1085 crit rating derived from fate): 4628

If the numbers I derived from my essence build are correct, it came out roughly even. The class set armour provides a total of 12,086 physical mastery (and 11,472 tactical mastery), and my build provides me with 10,934 physical mastery/10,320 tactical mastery. Because this is for a captain (and captains need both physical and tactical mastery), I get more bang for my buck by going straight might essences, rather than sprinkling mastery essences. The mastery ratings ended up a bit lower, but I gained more crit rating, crit defense, and a bit more icpr (from the extra fate).

* This may not be 100% final. If I do swap out the leggings for a slotted piece, I intend on putting the following essences on: (2) Might, (1) Crit Rating, (1) Finesse/Crit Defense/Resistance (I can’t decide).