When should I drop tank stance?

[Aana]

The damage penalty of Shield Oath is only 15%.

However, DRK lose 24% and WAR lose 25% alone for being in tank stance, so I guess you are right that PLD lose more than a fifth of his dps ^^

As an addendum, Sword oath was tweaked some while back. It is no longer a flat 75 potency/hit. It scales with your AA attack speed. it is 75 potency base at 3 second attack delay and will increase or decrease with sword delay. Prior to this plds focused on the fastest swords possible to get more 75 pot bonus attacks. Now it doesnt really matter. You can think of it more like a 75 potency DoT. Every 3 sec you will do 75 pot of damage. It doesnt matter if your attack delay is 2.24 or 3. Your average bonus from sword oath is identical 25 pot/sec 75/tic(3 sec).

TLDR: Sword oath is just a 75pot/tic DOT while in melee range now.

In addition, not sure where the 24/25% numbers came from. Drk looses 20% damage from grit flat. War (starting from 105% in deliverance down to 80% in defiance) looses 23.8% damage flat. You have to then factor in the wierd stuff like Fell cleave becoming IBs, loss of blood weapon, Blood spiller retaining its no-grit potency etc and it gets complicated real quick. But the base lose is 20% for drk and ~24% on war.