This interesting use of vocabulary emerges in one of Anne's first long speeches to poor Matthew as he takes her back to his home. In it she talks about her life in the asylum with other orphans and we have our first indication about her great powers of imagination as she talks about the kind of games she played when she thought about the other orphans with her. Note what she says:

It was pretty interesting to imagine things about them--to imagine that perhaps the girl who sat next to you was really the daughter of a belted earl, who had been stolen away from her parents in her infancy by a cruel nurse who died before she could confess. I used to lie awake at nights and imagine things like that, because I didn't have time in the day.

A "belted earl" refers historically to the fact that in England, up to the seventeenth century an earl was given that position and status symbolically by a sword that was girded around his waist. A "belted earl" is therefore an earl whose family received that honour from a great time ago, and thus "better" or "superior" to other, more recent, unbelted earls who had not received their honour in the same way.