This is Arrancar Perro's smaller blade, but unlike his katana, this blade is not a Zanpakto. It is actually to jaw of his mask reformed. The first one represents the control he has over his hallow intincts, but after he used Instinct Embrace in a fight the blade started to change shape along with him losing control over his hallow instincts. The plus side is every time it changes his powers get boosted.The final form it takes resemble his mask's jaw and a bit of the removed of his mask. #Bleach