This knife with a bell-like handle would be used at oranmila shrine to summon spirits and ancestors. The Aza are not frequently mentioned in works on Edo culture, which is likely because they are used on fewer occasions compared to the other clapper bells.
In English, the term bell is used to describe objects designated in Edo as Aza and Ẹroro. Whereas most Ẹroro are made from brass and some even from ivory, Aza are made from iron. The form of Aza differs as well: rather than sharing the quadrangular form of most Ẹroro, Aza are conical and have pointed protrusions at the top, sometimes in the form of a knife. Unlike Ẹroro, Aza are not featured on other objects such as relief plaques, and they are not written about much in literature on material culture from Benin.