...set in the modern age, Gryph?
It occurs to me that, if you followed this pledge through, you'd have a problem of power scale.
That problem can be summed up in three words: "JoJo's Bizarre Adventure".
Now, if you happen to dislike (hate, loathe) this manga/OAV/fighting game for some reason, then obviously you won't be including it and can skip the rest of this post. :) But I'll assume you're reading it anyway...
The problem is simply this: if following strict JoJo canon, even a relatively weak Stand User--say, the recurring comic relief villain Hol Horse--could kill almost every character who's even been mentioned in passing so far in SFWL. Easily, from a fair distance, and with no chance that the victim or any onlookers would be able to defend themselves in any way or even know what had happened or who was responsible!
<expository lump for the uninitiated>
A Stand User is someone who has the psionic talent--inborn or magically bestowed--to create a semi-independent field of telekinetic force, usually in humanoid form, through which a variety of weird psi powers may be focused. In other words, a Stand is an imaginary friend with l33t sk33lz. ;) It acts as an extension of the User, who may or may not be able to "see" through its eyes (if not, the User must be able to see his Stand to direct it effectively).
There are a number of "rules" that most Stands follow, but only one is unbreakable--and that one is the killer.
Stands, being pure TK, are what Bob Schroek would call "variable non-corp"--any part of their "bodies" can be solid to chosen objects and phased with respect to others. The only exceptions are those Users who must animate some form of matter to use their Stands effectively (Devo and his wooden doll, Iggy and sand, etc.).
Most Stands are invisible and inaudible to anyone who is not a Stand User; since no other psi talents are found in the JJBA manga, it's open to discussion whether other sorts of sensitives could detect them. The exceptions here are those whose powers involve illusion or shapeshifting (which must be visible to anyone or is pretty much useless) or, again, the matter-animating Stands.
Stands typically have very short ranges, and decrease in power the further they stray from their Users; ten or twenty feet is pretty damn far for most. Any Stand with an extremely long range is likely to be either pathetically weak or unbelievably powerful.
Any damage done to a Stand is reflected on its User--strangle the construct and the human can't breath, cut it and the User bleeds, et cetera. Some Stands are "armored", with reduced or negated injury-transfer; a rare few seem completely indestructible.
And here we come to the killer, the one rule that as far as I know has never been broken: No force other than a Stand can harm, impede, or affect a Stand in any way at all. The worst part is, before it became a story about psi combat, JJBA was a Street Fighter style martial arts manga... so we know, for certain, that ki has no effect on Stands. (Joseph Joestar--the second JoJo--is both a grandmaster of Hamon Sendou and a low-powered Stand User; only once did he ever even try, in desperation, to use his Overdrive ki-blast on a Stand. It failed utterly.)
</expository lump for the uninitiated>
...So you see the problem. n.n; Stand Users seem just a bit out of scale with the run-of-the-mill SFWL character types... how, if at all, would you guys address this?
(Joseph Joestar himself would seem the best pick for a cameo here--he's a crusty old grandmaster in a style that focuses almost exclusively on ki attacks. Hamon Sendou involves attuning one's ki to sunlight, allowing a master to kill vampires with his bare hands; JoJo-issue vamps aren't particularly vulnerable to anything but sunlight, and can even survive decapitation, so you can see where that would come in handy. :) Actually, I wouldn't be surprised if SFWL-Gryph's grandpa turned out to know--or to BE?!--JoJo II...)
"Blood covers The City like a big red afghan."
The Evil Midnight Lurker what Lurks at Midnight (YEAH BABY!)
Warrior Chef--Avatar of Virtue--The Muse of Deep Left Field