It is possible to acquire this weapon style by besting Sir Roderick in a challenge of wits and afterwards a battle.
A strange weapon from a strange culture, Mirabelle is made of wood and steel and emits thunder and fire. Loud and ungainly (like its previous owner), Mirabelle is nonetheless capable of doing real harm at medium range. Etched with undecipherable symbols from the Outsider's language, this weapon is a unique (and dangerous) trophy. The power of some enemies is such that fate itself turns away from the cold, foreign steel Mirabelle projects.
Mirabelle could be called the best ranged weapon in the game. It has high damage and great range. However, it must be reloaded after each shot, and the power attack requires additional loading before it can be executed. This reloading takes up valuable time that enemies can use to close in. In addition, the Player is unable to roll or jump while wielding Mirabelle, severely limiting his or her evasion and movement. When first acquired, Mirabelle drains focus extremely quickly and can use up a Player's entire focus if they are not careful. However, upgrading the "focus cost reduction" on Mirabelle helps to counteract this effect quite well.
If you switch to another style while performing an attack animation for Mirabelle it is possible to completely bypass the recovery animation (reloading animation) that renders the player unable to move. Simply initiate an attack and directly switch to another style, the attack will go off but the recovery cancels out.