Ceding the point that seeing it that way it is indeed the best armour debuff, and assuming they are both pretty swell damage
wise, we are left with:
WL: Armour debuff, pounce to attack/save yourself, with said drawback of needing a target, different pet skills depending on your stance, less squishy than a slayer/WH
Mara: Wounds debuff, heal debuff, same armour debuff, monstro stance dance to harden up for focus fire, less squishy than a choppa/WE
We are still talking group play, yes? Since 1v1s don't matter. So a punted WL's pet won't kill you, unless your healers hate you.
Mid air pounce should be fixed by now, too. It's a nice little source of sustained DPS while the WL is gone, until you make it prio to
focus the pet with your group DPS and it indeed dies pretty quickly. Shares the downside with squig pets. More a nuisance than anything, unless you get solo ganked on a none healer class.
Still not seeing the terrifying deadlyness since the pet alone can easily be outhealed. Pet pathing is certainly better
than on live, but it's still fiddly and more often than not a downside proportional to the level of play you're in.
Should the solution to a high risk offensive play like a pounce into enemy lines really be to take the bite out of his attack power by stripping off the armour rip, or maybe rather, if a nerf had to be applied, in making the WL squishier? To me it should be the latter. Less attack and more resiliance for the sustain frontliners, higher attack and less resiliance for risky fighters.
Squigs need some love eventually, too, I give you that. Super long cooldowns are awful. There is the "I got lots" tactic, however. At least you could summon something else while waiting. As WL you could bridge the time by using up a tactic slot and would still be butt naked for a few seconds, or get rid of the pet and the cc with Loner. Both could be better, really.
Nobody is denying that this game's balance needs some fine tuning. Still not seeing a very clear reason to hit the WL with
a nerfhammer explicitly. Both factions need better inner faction balance. Mara having the holy trinity is just bad not for order, but destro itself. Also: No matter which class you stick that armour rip to, they'll always deal more damage since armour is such a huge deal in this game. Just imagine a slayer with an armour debuff instead.

Some order melee DPS has to have it. Wouldn't stick it onto WH/WE since their mechanic already is to ignore a big chunk of armour.