It will be observed that while the statute does not, in terms, require testator to sign in the presence of the attesting witness, it does not mention acknowledgment as a mode of execution. What does "attestation" mean? Webster says that "the subscription of a name to a writing as a witness" is an attestation.
Ivan W. Goodner,
Notes and Comments,
Does Washington Law Require Testator to Sign His Will in Presence of Attesting Witness?,
6 Wash. L. Rev.
Available at: https://digitalcommons.law.uw.edu/wlr/vol6/iss2/3