Here's how to fix TBN

[Weetzlo]

You'd then have DRK's EW trait essentially grant up to 40 seconds per minute (67% coverage) of 10% mitigation, as opposed to the up to 16% coverage of the others' traits.

Put more simply, your suggestion must be compared against Knight's Resolve (10% miti, 4s) and Knight's Benediction for PLD (1000p HoT), Catharsis of Corundum (900p excog) and Clarity of Corundum (15% miti, 4s) for GNB, and Stem the Tide (10% miti, 4s) and Stem the Flow (400p shield) for WAR.

Does an almost 50% increase in coverage of that mitigation fall below the value of those 2 self-heals/shields per minute?

Moreover, given how DRK uses TBN, is that where you most want to apply, inseparably, that added defensive value per minute?

You're not going apples:apples here. You have to look at the whole ability, not JUST the EW upgrade. Holy Sheltron lasts 8 seconds. Only 2 came as an EW upgrade but considering the first 6 seconds came at level 35 where DRK has 0 parallel so it has to be ability:ability not just EW parts to EW parts. It's not like I can just use the 2 seconds of block and 15% for 4 seconds individually. Sheltron lasts 8 seconds and charges in 20 seconds of melee uptime. 40% uptime. Wilford's 67% is out of line with that but considering all the other tanks have half their uptime be at double strength, having more uptime but weaker wouldn't be the craziest thing