In the normal state of the Feat 'Thunder and Fang' from Varisia: Birthplace of Legends, it reads:
Normal: An earth breaker is a two-handed weapon, preventing the use of a klar in one hand without imposing penalties for using the earth breaker one-handed. A klar can be used either as a one-handed weapon or a shield; it does not grant a bonus to AC during rounds in which it is used as a weapon.
What does "preventing the use of a klar in one hand without imposing penalties for using the earth breaker one-handed." mean?
How could an earth breaker be used one-handed without having this feat?
