Does Fi wear enough clothes to conceal a firearm?
Rarely.
Bless her heart.
(Bikini photos, racy but probably SFW)
There are holsters that strap to the leg and are positioned on the inner thigh.
The point of both of them in swim suits in that episode was to approach the bad girl proving that they had no wire or weapons.
02/19/2009 She had a skirt below the knee where she could have had something taped to her thigh. 
She could stick one in each intercostal space. Damn, she’s skinny!
It’s a matter of misdirection. Fi has a way of making you not look at the weapon.
Standard Heinlein story device. Hot chick is buck naked, then pulls a gun out of somewhere but the witness has no clue.
Shut up and enjoy! 
I always thought she was attractive enough except her face has sun damage. I guess that’s what Florida does to you.
Here’s what I remember her as: http://ak.buy.com/db_assets/large_images/734/40222734.jpg
All in all, I think she’s aged VERY well.
She’s never been shy about showing her “weapons.”