Actually, in canon Precia is rated as a natural SS. That's in HAYATE's league after she's Unisoned with Rein. That's planet-busting level. One step below the Sankt Kaiser, actually. One theory is how she hasn't keeled over yet from the mana reactor explosion that put Alicia into a near-death state. She's used to handling absurdly high levels of magic, so while she still gets radiation poisoning from a mana overdose, she has survived for at least a decade when most would have died. Hell, even when half-dead she hurls a bolt of lightning across dimensions that is powerful enough to disable an entire ship. That's power right there, and skill to go with it.
Anyway, just saying that she wouldn't be curbstomped quite so easily. Sure, powered by Mettalia Beryl would win, but it would by no means be an easy fight.