Parry...

[Casper]

No worries! I was under the impression that a Hard cap is the highest attainable from available gear, and a Soft Cap is the highest usable amount of a stat. I always thought Diminishing Returns were in a different category, but a lead in to what I had understood was the Soft Cap. So, thanks for correcting me!



Ok, Looks like there needs to be a consistent standard set on how much damage you can deal with, and without Determination/Crit, because that number you pulled makes no sense to me, unless your parser works differently than mine does.
If we ignore secondary stats all together:
I was using a Wave Buckler to maximize Shield Swipes. 3xSS are greater potency than 1 RoH combo, so I only use RoH when it's about to fall off, or when SB has connected, otherwise SS is higher priority.
Your lodestone shows you using the Noct Hoplon, If you were using that shield, you should generate way less opportunities to use Shield Swipe.
So that alone should give me a huge potency edge by the 3 minute mark in how much damage was dealt. (Unless you got super lucky, and blocked the same number of times as I did with a Buckler)
Which is the next question I want to ask you. How much total damage did you deal in that fight? I'll get my number and post it soon. (I'm at work now)
Also, did you Main Tank, or Off Tank? and Did you clear the boss?
On a Training Dummy, I get a clear 30~ DPS boost in my DPS gear over my Parry gear, and that is without Blocks adding more potency, so my in combat DPS is higher while standing still on a boss like T7.
So your stated number ALSO bothers me because I have more strength than your lodestone profile(If that is the gear you were in) by at least 10 points.
Your DPS number is either flat out wrong, or your parser is badly configured. Because stats can't enable you do pull those numbers.

Roh is 203.3 average potency, SS 210. Difference 3%. The truth is, this is among the standard deviation over a fight given the deviation of attacks by + to - 5% and the crit chances. Not saying you wouldn't gain a tiny bit here, but 3% difference, on 17% more attacks (due to block rate going from 21 to 38) is a 0.5% dps increase... given that you are doing around 130 dps, that's not even 1 DPS of difference. 10 str is 1.5% more damage. Total for both is about 2.5 DPS of difference.

Did you have a warrior ? Did he keep the buff to slashing on the boss ? If you go double pld, for example, that alone would be a much greater factor.

Your 30 dps boost, do you mean in dps stance ? Cause going from 100 to 130 or 170 to 200 is not the same. When you say dps gear, i assume you mean, literally, dps gear, so with str instead of vit ? Because yes, in that case, i could see a 30% damage increase. But you are not talking about sacrificing parry only here, you are sacrificing a lot of vit too to get there. 250 parry into full det and crit, plus 75 vit into str, sure, maybe we are getting closer to 25-30 dps increase, but you did not only lose almost 20% parry rate, you also lost 1k hp.