With respect to Burst I dunno, I just don't feel 20 seconds is really a "burst" timeframe, maybe my issue is with the terminology.
I think I might have confused you with my relative words also. The WAR took 27% more damage than the PLD. But that's using the PLD as the "baseline." So Block didn't reduce overall damage taken passively by 9%. That would have been if PLD took 27% less damage than the WAR (which wasn't the case). The PLD took ~21.3% less damage than the WAR, which puts the shield block contribution really, too low in my numbers.
Or maybe I caused the problem by flipping it around from healing load reduced to WAR needing x% more heals which is the way I like to look at it, since it's the real world impact of going with a WAR over a PLD: how many more GCD's do you need to keep them up?
Now that I think about it, I really don't trust my FFXIV APP tracking very much at all in terms of damage taken, so maybe that's the biggest issue.
But my parse showed me blocking 21.9% of non-miss attacks, (202 Blocks of 869 hit, 45 crit attacks. Should be a contribution of ~5.5% damage reduction. This is with Holy Shield. +1 should probably take it up to 6% I think, between the rate and block value increases, though I may be wrong (if it doesn't then I don't think anyone should ever upgrade to Holy Shield +1...)
Also my testing with Rage of Halone had a contribution of ~8% damage reduction (19.94 damage taken v. 21.63 damage taken) though I suspect this to be wildly off because it's the APP parser and because of how hard it is to test halone. It's actually kind of hard to test this in a meaningful way, because even with the weakest weapon the mob dies before it can get a lot of attacks in, and mob damage seemed to drop off quite a bit once they were up for a long time (testing without halone was ~100 hits, w/ was ~30).
This was against the lvl 49 cohort Eques (lancers).