
Originally Posted by
Lyth
No. Starting from Deliverance at max HP and cycling through the stances, you end up at the same HP when you complete the cycle regardless of whether you received heals or not. If you didn't, cycling through Deliverance and Defiance would progressively drop your HP until you died. This sort of implementation wasn't uncommon in older MMOs (looking at you, Last Stand).
Defiance creates a temporary HP buffer which you and your healers may or may not decide to take advantage of. Actually, any time you leave Defiance at less than 80% HP, that buffer isn't being used anyways.
Shield Oath is set at 15% because you lose auto damage when you're not in Sword Oath. Autos are generally one of your top sources of damage. The damage gain from Darkside hasn't been changed, and is functionally analogous to how Storm's Eye (or the old Maim) works. It has nothing to do with "negating" tank stance. It's a job mechanic that has to be correctly executed in order to reach your baseline potency values.
The drop in the Defiance penalty was added in response to adding resource costs to WAR's stances. This was a case of every job needing to have equivalent costs, or none at all. When those costs were removed, the penalty was not reverted. Not that it particularly matters, though, because having Unchained without any resource cost attached provides a workaround to the damage penalty, regardless.
The instantaneous enmity effect of Defiance is its single most important asset. The fact that you can weave Defiance, Equilibrium, and Onslaught in your initial enmity grab, on top of having Unchained for free, gives you a lot of snap aggro for virtually no cost. If you could independently replicate that effect on the other tanks for free, oGCD vs GCD swaps wouldn't be so important. It's not like you decide to change stance the second before a tank buster, anyways.