I love Shae, so I guess I'm being biased here =)
She's a local, like Harec, so that means they've got the same traits (low health, high stealthiness, high risk melee).
She's also a sniper, but I find her more suitable for my playstyle than Harec: you don't have to be super precise with her aiming, just keep the target in the center of the crosshair to maximize aiming speed and damage. Oh, and long range also helps aiming faster than short range!
As for the Bewitching, I find it super useful when you've got a Lycus running to you with his Shield on (countering your shots) so you can escape and even grapple him while bewitched. Remember that Bewitching loads quicker the more targets you have in the crosshair, so it's better to cover as many enemies as you can and then fire it. That also helps when you're a Raider: you don't need to only aim to the Antagonist, make use of the AI to fasten the load! It also makes grappling super easy, so recovering ammo usually is a no-brainer. Beware, though, the enemies that aren't bewitched can still see you!
Focus Kaa7 is a weapon that behaves much like the original but doesn't need to focus on a target. Instead, its damage and fire rate are affected by how close to the center the target is. That also means more frequent reloads, so you need to time your shots right.
Long live Shae!