When weapons with sharp and cutting edges are brandished, a vaguely metallic sound effect will be inserted (along with a bit of Lens Flare) to signify just how lethally sharp the weapon is.
The tone of the sharpness, as with musical instruments, is dependent on size.
A katana makes a tiny, high-pitched sound; the stabbing metal arms of a Humongous Mecha are much deeper, but fundamentally the same [...] [tvtropes.org]