Interestingly enough, the simple mention of black leather gloves and blades immediatly identifies the stereotypical Giallo killer.
Of course, there's nearly always a 'whodunnit' component to gialli. But when you think about it, knowing who the killer is never is the most interesting part.
How the killer will strike. With what perversity. In what fashion.
How stylishly he will strike. That is the interesting part.
Giallo killers have no face. They don't even wear a mask, or exhibit monstruous faces or use any specific device which would identify them as individuals. What we focus on is their hands, these black leather gloves holding sharp and shiny blades.
These arms are not a man's. They are the arms of Evil. And Evil has no face for it can strike from anywhere, using anybody's arms.
The Giallo killer figure, much more than a character, is actually very conceptual: a symbolic face of Evil.