Wash. Rev. Code § 9.95.015
In every criminal case wherein conviction would require the board to determine the duration of confinement, or the court to make such determination for persons committed after July 1, 1986, for crimes committed before July 1, 1984, and wherein there has been an allegation and evidence establishing that the accused was armed with a deadly weapon at the time of the commission of the crime, the court shall make a finding of fact of whether or not the accused was armed with a deadly weapon, as defined by RCW 9.95.040, at the time of the commission of the crime, or if a jury trial is had, the jury shall, if it find the defendant guilty, also find a special verdict as to whether or not the defendant was armed with a deadly weapon, as defined in RCW 9.95.040, at the time of the commission of the crime.
RCW 9.95.015
Effective date-Severability-1986 c 224: See notes following RCW 9.95.001.