No it does not, WAR does not give any Defensive bonus outside a couple points of VIT possibly, because the DEF Bonus WAR gets at lvl 10 does NOT stack with those on PLD. Only thing you are losing is Defender, in which your hits become even more pathetic.
Next time, read the thread linked. The BLU at the start of the battle in one of the videos there leaded the battle with a couple hundred points of damage, and even PROVOKED and could not steal hate. Provoke if you did not know is only spike hate, and only holds hate at the beginning but quickly loses its hate spike. Enfeebles however are perpetual hate and stay with you unless hit, if those enfeebles do not give hate,
then you are advocating that NINs cannot tank and should not use enfeebles for hate at all.
What are RDM job traits? Fast Cast, it lowers your Flash recast timer by a certain percentage and has upgrades every now and then. This is alot better than Provoke by a large means, because Flash is only 25 MP which in only 15 seconds(Sanction Refresh, Refresh, and Auto-Refresh) will regain back. Not to mention blind the mob serverely so that you take almost no hits at all while gaining perpetual hate.
Theres also Magic ATK Bonus which affects Seraph Blade, instead of doing 150, Armando can do alot more damage up to 300 + damage a Weapon Skill. A RDM/WAR can definetly tank, and in this case its about the same thing. And not to mention Magic DEF Bonus which is practically if i remember right, Shell1 casted on you forever. Not to mention Clear Mind.
Next time read the thread, the OP doesnt even recommend this until you get Refresh from RDMs to counter the MP lost from spells. RDM sub does not gimp your DEF at all except maybe a couple points of negligible VIT. In which parses on that very same link i posted shows that the tank took less than 600 damage on some, because he was able to Flash + Blink Sickle Slashes. /WAR however definetly takes MORE damage because you have to take them in the face almost definetly. +Enimty also helps with keeping hate, whilist Cover can give you that edge that Provoke has in help turning the mob when needed.
must have been pting against other mobs, or your friend wasnt using the same gear, because a RDM sub, i assure you, gimps your defense.
I know this player just as well as the poster you quoted, and trust me, he wasnt wearing any different gear, in fact he probably would be wearing BETTER gear than before since he is slowly getting his AF pieces.