Not sure if you're aware, but winning all six WKR will give you many rewards, not just the one for RoE.
At the Library in Eastern Adoulin, you get to pick a reward at each of the following points:
1) First time you defeat all 3 of Ceizak/Foret/Morimar: choose any of the low level (item level 106) items they drop. These aren't really any good now, can get better gear with RoE sparks or even bayld.
2) First time you defeat Marjami/Yorcia: choose any one item dropped in those two fights. NOW we're talking, some really nice items here including Tamaxchi, Uk'uxkaj Cap, Pahtli Cape, etc.
3) First time you defeat Ceizak/Foret/Morimar/Kamihr: choose any of the higher level (item level 115) rewards from those zones. Note that Ceizak/Foret/Morimar must have been defeated after the Nov. 2013 update when the content level of those Naakuals were raised.
Above quests are not repeatable. However, the RoE quest for turning in the full set of temporary key items from winning WKRs (and selecting any WKR drop) is repeatable as many times as you like. You CAN do these at the same time, so making sure you have RoE quests on and killing all 6 WKR means you get your RoE reward AND all of the Library rewards described above.
Oh, and of course you also get the direct drops from actually fighting in the WKR. Includes not only the special weapons and armor from the WKR, but also a random chance of the Job Specific capes (which can be traded, any three for one JSE cape of your choice, also at the Library).