I've just looked at the first post and if Mia's still lacking a suggestion she could "charge" for ~1s then fire a projectile, as she does on holding CTRL with full health in the game.
I'd be pretty lousy at describing it any better but I could crop down a few screenshots to illustrate if you're not familiar with it.
Edit:
Eugh, could anyone suggest a halfway decent image-host? Couldn't upload to photobucket, hopefully imageshack'll do for now.

1. She crosses her left arm over her chest, looks up and closes her eyes.
2. She levitates off the ground while her "weapon" grows. While she's fully "charged" and the button's held, a tiny lightning-bolt intermittently forks off the weapon.
3. When the button's released she swings her weapon down and left (her left) which launches a fireball ahead of her.
It seems to take about half a second in-game but she could be made to wait for watever length of time seems appropriate. Also, the "weapon" (a small, yellow triangle similar in appearance to a gas-flame, at the start) gets larger as it's upgraded in the course of the game but I don't have any late saves to demonstrate that.
AnotherEdit: Remembered two of the thrown weapons and found out about one other. She finds Daggers (straight trajectory), Hammers (travel in an arc) and tridents called Mojaks (I think) which also travel in a straight line but can stick into walls and be used as platforms.
[..]Some more hunting around has offered up the Sigil as a possibility.

It turns enemies it kills into bunnies so it could offer a more memorable effect at the cost of a little more spritework (a bunny walk-sprite). On the flip-side it could be pretty irritating for anyone on the receiving end.