Answering your question:
Those are fine in WA, and are considered a simple single-edged fixed-bladed knife.
Unfortunately, all fixed-bladed knives are banned in Seattle, so keep out of the big city with it. Yes, this even applies to the 1/2" models.
Commenting on your question:
If you have the free hand and ability to use it in time, direct physical retention techniques would be a better use of your hands. A situation where this knife would make the difference to help you keep or get your gun back doesn't seem too likely. It seems more likely that going for the knife could slow your response. Still, what you want to carry it for isn't too important. My point is that you shouldn't consider this too major of a part of your retention plan.--Sandy (WA)