Hmm, I'm trying to imagine what tactics a 'vulnerable' bully would use.
I just get the plain bully. No special tricks.
I actually bought and read two books because of a bully at work. Games People Play and How to Deal with Difficult People.
They gave me a bit of insight, but weren't much help.
The best advice I got was from another co-worker when I finally voiced my dismay during a coffee break. (I abhor office politics so I rarely discuss work problems with co-workers).
Anyway, her advice was to just let the bully talk, and bully, and look like an ass. Then go and do or not do as I had planned. It worked. Once she realised she had no power over me, she moved on to someone else.
Either that, or she realised that without me sticking up for myself or arguing, she didn't look like a 'strong, thinking, make-things-happen woman', she just looked like a bully instead.
We have a stress relieving statement we make at work, when things start going downhill, "Strap on your helmet" (because you are going to start banging your head into the wall at any moment).
Just walking past someone and quietly muttering this phrase lets them know that we see what they are dealing with and commiserate. And it makes for a good laugh.