Both. If they don't think this is a bug, then request that they make our JAs not lackluster and function the way the people that actually play the job would want it. No reason that Saboteur shouldn't do something significant for every enfeebling magic at this point, though it blatantly doesn't. It should be extending the effect and the duration of what is significant about the enfeeble.
No one uses Dia III as a DoT, that is what Saboteur-ing Poison II is blatantly for (Seriously SE? No Poison III yet?). The effect that should be modified is the defense down on Dia III because that is what Dia is used for. Bottom line, fix RDM already SE, it's broke as a joke and the joke stopped being funny years ago.
