The signifier was intended to be the Nerazim variant of the high templar. In the final product, it is replaced by the dark archon as the Nerazim psionic warrior. The signifier exists in the map editor but is unfinished; it uses the high templar's model along with most of its animations and sounds, and its wireframe tooltip is the same as the dark archon.
The signifier is permanently cloaked and moves faster than the normal high templar, and has the same psi attack they do. It possesses the high templar's Feedback ability, and instead of Psionic Storm, can use "Crippling Psionic Storm." Crippling Psionic Storm acts identically to the normal Psionic Storm, with the additional effect of inflicting the "Crippled" effect on enemies, sapping their armor by 5 for 10 seconds.