Another interesting reference is a 1964 article by J.J. Rodriguez Lorente, which suggests criteria for distinguishing ear daggers of Moorish, Spanish, and Venetian craftsmanship.
The XVth Century Ear Dagger. Its Hispano-Moresque origin
The article mentions a large collection of daggers held by the Museo Lazaro Galdiano. Nine daggers appear in the museum's online catalogue:
Museo Lazaro Galdiano
A little drawing by Hans Schaufelein (c. 1510) shows that Northerners were also aware of this style of dagger, and made use of it at least as an "exotic" artistic element.
Hans Schaufelein, Archer Drawing His Bow