So what exactly IS the issue with Warrior?

[Maelwys]

I don't know what the reason is, but every parse I've ever seen with 1 WAR and 1 PLD has had the WAR a good 20% more damage in front of the PLD.

When the maths says one thing, and the tests say something else, I start thinking maybe there's something the maths hasn't accounted for.

One reason might be WAR's damage resistance debuff.

Most impartial "same-gear/stats" parses I've seen have been a bit iffy on ability rotations... and I'm really not sure why, because PLD's rotation is ridiculously easy: Spam RoH combo, use SW and CoS and FoF on cooldown. Shield Swipe and Mercy Stoke if they pop up. [Optional: Fracture after it wears and you're not mid-combo - IIRC it's a very slight gain in PLD DPS. Usage will depend on TP level: if you're likely to bottom out, don't use it]. Job Done.

If you pick Random Tanks in game (not purposely equally geared/stat'ed) and ask them what their DPS is like, it's another matter...

Firstly, in game more WARs tend to have +Str (via gear and/or point distribution) than PLDs - because of the mob "Must increase Self-Heals" mentality. The flip side is that PLDs tend to have more +Vit for the same reason, so they're generally seen as a lot tougher than WARs before you even factor in cooldowns. If you pick a random WAR and a random PLD, then stick both in i90 Allagan armor and melded Gryphonskin accessories... then chances are they'd be a LOT closer in both damage and survivability.

Secondly, on a lot of endgame content PLDs tend to use "Circle of Scorn" pretty much on Cooldown, but save "Spirits Within" to use situationally. This is intentional - Silence diminishing returns is a [Censored], which means you have to be rather careful with SW usage on the likes of the later half of AK (Succubus) and certain Coil Turns...