Originally Posted by flarmip

For BA-operated flights, hand baggage only fares really do mean HBO. Your status or the class you're travelling on a later flight aren't relevant, so you'll have to pay to add a bag. Don't think you get a second bag for free when paying to add a bag, though I might be wrong on that.

For flights operated by most other OW airlines, including AA, status does grant you a checked baggage allowance on a HBO fare.