I guess to start, stances wouldn't really work without a full redesign of the job. Granted, this could work assuming we wanted to just finish ripping off Bloodborne by making the RDM stances correspond to weapon modes like the trick weapons from that game (instead of holding the sword like a decoration and then remembering its supposed to be used like a staff). Sword swung with the main hand while the crystal in the offhand is used to cast weak spells, then bringing both together to cast bigger spells. Of course, this means melee would have to play a bigger role in the design, but thems them breaks.
In the short term, the job could use potency boosts to stuff already in place. I'd probably replace Enhanced Displacement (Displacement and Engagement should have the same potency, otherwise you're punishing the player in situations where they can't jump away) with a trait that boosts Verfire/stone/aero/thunder. Of course, the potential issue with this is that RDM DPS output becomes very dependent on procs (Jolt II vs boosted Verfire/Verstone). I guess we could lower Acceleration's cooldown to 30s to help with this.
The more roundabout way of buffing DPS output would be to increase mana gained per spell cast to increase the frequency of the enhanced melee combo (since that is supposed to be the burst phase). Doing this, however, would require increasing the threshold for discrepancy between black and white mana (the current threshold is a difference of 30 between black/white mana; you'd need to increase it to 40 or 45).
Frankly speaking, I don't agree with the notion that utility somehow inflates RDM's value beyond its intended role. Whatever applicable taxes should not lead to the gap in DPS that we're currently seeing. So I'm gonna have to say that I don't think Vercure and Verraise should be locked away as the OP is suggesting.