*sigh*. If it's one rpg canard that wears down the soul, it's the idea that players have to take a backseat to NPCs. Not PCs -- the players themselves.
There is no aspect of the setting -- none -- that does not exist for the players' entertainment. And that includes the GM -- they're all social equals. As such, if the group is made happy by the given power level of a game object, even though it may rival or surpass some NPC, then that object is an inherent good. Demanding that the group supress their preference is no different than persons in real life becoming desperately concerned that a stranger, in the privacy of that stranger's home, may be doing something that the said persons don't approve of.
Puritanism: The haunting fear that someone, somewhere, may be happy. -- Mencken
This is made more clear by the fact that the setting doesn't even implicitly, not even reaching explictly, trump the power level of the artifact at issue. Who's to say that the only thing that the swords do is what they've been seen to do? Who's to say that the swords' power levels and abilities aren't affected by their weilder? Those swords could be more powerful than what's been seen. Or they could be a lens for the true power of their weilder and contain little magic in and of themselves. The swords' uniqueness is also unconfirmed, and the virtue of said uniqueness is a totally fact-free matter of opinion: it is purely a matter of taste. (It would be fun for some if powerful artifacts, regardless of the source, followed similar patterns, for example.) This world background's metaphysics have been
staggeringly unexplained. And since the author of said background's name is up above our text box in titanic 72-point type, we can safely conclude that that was intended as a design feature. Indeed, the rpg's vagueness on basic aspects of magic isn't always a feature -- it's often a flaw for some -- which is why we're here.
If someone sits down and plays the Dresden Files rpg and decides that her PC servant of Vishnu has more cosmic juju in her gear than anyone elses toys have in the universe and her group loves the concept, not only are they not "wrong,"* they're playing a roleplaying game right.
*The worst they could be is directly contradicting canon, and that's clearly not going to be the case until Butcher's next rumored book "Christ Rulz, Vishnu Drulz" hits the shelves. I find that rumor highly dubious.