In the space of one book ...
Ummm... not really? We've been seeing Butters "brave up" for several books, beginning with his attack on the un-Coin'ed Cassius, and being Harry's drummer for Sue. Harry has been cheering him along, mentoring him, lifting him up. "His nerd penis is bigger than all of yours."
But remember: that moment with Cassius is the scene where Waldo Butters was the answer to Harry's prayer that he be
saved by a Knight of the Cross. He was a "Chosen One" figure from then onwards! Even if, literally, he was an ankle-biter there.
Yes, he
is rather a fanservice character... began, honestly, as comic relief / nerds' nerd, but he was surprisingly popular, so Jim gave him more and more role, more and more agency.
But
Changes represented more than one kind of "Change," and one of the things that has happened is that Harry's now working at the power-scales where un-boosted mortals can no longer survive (not even with a bit of Harry's attention on shielding them). If Butters is to continue, he needed a
major power-boost.
in
Ghost Story he has stepped up to being a really-active member of the Chicago Alliance, working the streets; and also their conduit to Bob's magic-theory & supernatural knowledge (taking over (that part of) what Harry had been doing for Chicago... if you don't have Harry, it takes a
magical village! ). This is, I daresay, braver & more daring (on a daily(?) basis) than most people manage to be
even once in their lifetimes (of course, most people aren't facing the kinds of threats and risks that Butters has, and don't have the
opportunity for that kind of daring...) . But he's already an "action hero" in this book!
But you know what? Being a magic-geek (with Bob to mentor & to be the needed "magic battery" for Butters' toys) isn't the kind of power-boost demanded by Changes. In comics' terms, Butters is only a "street-level" hero; but Harry dying & coming back is 2-3 notches up from there.
I think his scene at the end of GS (getting CPR, where he wakes and -- on death's doorstep & in tremendous pain -- nevertheless makes a nerdy-yet-gallant compliment) is what flips the "loverboy" switch on; who
wouldn't be flattered to be told they are someone's "dream," to be worth the effort to
compliment... when most people would just be worried if they were even going to
survive?
In
Cold Days, we see "loverboy" already switched-on, from the first interaction.
Then,
Skin Game. And the lightsaber... ah, the lightsaber... Butters (already menage-a-trois'ing with 2 (hot, younger) women) gets the nerds' ultimate fantasy toy; and becomes a Jedi Knight (of the Cross).
Face it: everybody's jealous that Butters gets a lightsaber... even the fans!
###
The thing that I think many don't realize is what the Swords actually
do.
People talk about the "superweapons" (from Hades' vault) and say they're "stronger" than the Swords. That's not (at all) the case.
If one of the Angels inside one of the Swords had stepped forth to do battle with Ethniu & the Eye, they could have put Ethniu over their knee, spanked her like a child, and given her another 3-4 millenia timeout. Or, y'know, just killed her out of hand.
But that's not their job.
The Angels in the Swords have a very specific role: they even the odds. No matter how potent the adversary, the otherwise-merely-mortal Knight of the Cross is on more or less even footing with ANY foe. The power-up from a Sword scales upward to whatever is needed, without any meaningful limit; but it's not delivering Drakul-facing power when a Knight is only facing a single junior Blampire.