“Checkmate” targets 1 “Terrorking Archfiend” on your side of the field as a target when it is activated.
Netrep Rulings:
“Checkmate” is a targeting effect, targeting a specific “Terrorking Archfiend.”
If “Terrorking Archfiend” is equipped with “Twin Swords of Flashing Light – Tryce” when “Checkmate’s” effect applies, “Terrorking Archfiend” may attack directly twice.