bold to assume he has only one gun ...

The answer to that question is a loud, clear yes.

Also there's a very good chance this is why she gets shot. If not by him, then by a member of the team he mentioned would be arriving soon.

Now, now, what is she looking for in this?
I'd assume she would simply want to convince Klaasen even if through intimidation, to get her leave with Tobi and Three, but maybe she's looking for more, maybe info, maybe confirmation of what Maria told her, maybe details of it.

Now, it would be a surprise if the one who shoots her is Three, with the gun she leaves in the ground away from Klaassen

Why yes, yes she has and we're all pigging out on popcorn waiting for what she does next.

Yep, she is paranoid... with reason ?

I can't really blame her. Like, I can make real-life comparisons to people (and entire nations) that I would like to give similar instructions to.