My understanding is that it’s forbidden to use or even know how to weave balefire, but not to know it exists or what it does. Knowledge of its existence moves around among Aes Sedai quite a lot without comment throughout the series.
Letting Novices and Accepted even know it exists is probably bad conduct, if not forbidden though, lest someone lacking sufficient discipline be tempted and try to learn to use it.
My understanding is that it’s forbidden to use or even know how to weave balefire, but not to know it exists or what it does. Knowledge of its existence moves around among Aes Sedai quite a lot without comment throughout the series.
Letting Novices and Accepted even know it exists is probably bad conduct, if not forbidden though, lest someone lacking sufficient discipline be tempted and try to learn to use it.