My partner runs Breton Ballista
The key goal in this build is to swap weapons only when Magica is low (as blocking disables the regeneration of whichever stat is attributed, swapping from staff to shield will allow magica regen).
While your shield is up, your magica should sky-rocket to full well before you deplete your stamina, then swap back to your staff.
Also, this build was built with a DPS partner in mind.
In PVE, I always have a DPS partner stuck to me to keep that guardian bubble active (8 meter radius).
The arctic wind keeps heals feeding into your partner, so even the squishiest DPS can live through boss AOE's and Cleaves.