How about a hexblade/spellthief, with Master Spellthief? She could steal spells as well as sneak attack, and she'd be decent in a melee. Charisma would also help both classes, and her spellthief caster level would be good, not to mention she'd be able to cast spells better than a hexblade. Loss of BAB is a bitch, but she only really needs 4 levels of hexblade, then one of mindbender, then 7 of spellthief. If she can go all the way to spellthief 13 that's great too.
If that doesn't work, a Hexblade/Paladin of tyranny is great, though that's a bit dark.
Oh hang on... She's expressing interest in multiple levels of mindbender? Wow, you're screwed. Umm... Reflavor a bard? That's probably the best mix of fighting, spells, and charming.
I have a divine bard11/cleric 1 that I'd like to pimp for a second. I'm actually thinking that he'd be better as a Divine Bard10/Cleric1/Contemplative1, with a choice of either more contemplative or more divine bard. Contemplative to get War or Strength, unless (please, god) there is a single domain that grants a beautiful combination of both Divine Power and Righteous Might, in which case I will turn purple and dance around in a fluffy hat. Cleric takes Planning and Undeath. See where this is leading? You can persist righteous might as well as something like Greater mirror image or greater blink. The rules of adding domains to a spontaneous class let you learn divine power/righteous might, whichever you like or both, and with only 1 extra turning (plus undeath domain), you can persist 2 buffs per day with only an 18 charisma. it gets way better if you pimp your turning with nightsticks, extra extra turning, and more charisma. My feats for this guy were lyric spell, combat panache(swapping for melodic casting, only took it because I didn't have access to the book), and the persist/dmm chain. This build keeps the spellcasting part around the level that your other party members will likely be able to handle, and it fulfills the criteria of her build. It even wears heavy armor!
Now, keep in mind, this bard character I made was actually an undead (bone creature, but necropolitan works), because of the sexy sexy immunities, the loss of CON for bigger hit dice and, most importantly, to solve the MAD. Divine Bard requires wisdom and charisma, as opposed to just charisma. If I hadn't lost my CON score, I would have had like 40 hps, nowhere near enough to wade into melee. If you get temp HPs from heroism and such, as well as take improved toughness, your HP will be fine. Also, I didn't take cloistered cleric, but if you allow it, pimp knowledge devotion. I used the bardic knack in this build and I frequently casted improvisation, which should work nicely with knowledge devotion to make this build fair much better in melee.