I tend to prefer Frailties based on the character's background and/or Fae nature. Some I've used:

For a character who's a teacher and bookstore owner, he *can't* give away information for free. There must always be some manner of price (though he's creative about that - for important things, the price of the information is that you have to *really listen and pay attention*

For a character who was a weaponsmith in Arcadia (and then was even more horribly traumatized by seeing what his weapons did to people) he can't touch a weapon and leave it as a weapon when he's done...