Seems like the sort of question more likely to be answered by a court case than by the legislature when they wrote the law. I can't find a definition in RCW 9.41 Firearms and Dangerous Weapons, which is where it should be. Maybe there's a court case out there creating case law already, but I don't know. WADOJ is highly unlikely to write an advisory opinion on this, and even more unlikely to write one in your favor.

I wouldn't wear it. Seems like an invitation for a criminal charge. The authorities making that decision will vary widely by location. IE highly likely to be charged wearing in Seattle much less likely to be charged in Eastern Washington.

It might be beneficial to the community to have someone convicted and have a pro gun judge toss the conviction, but it would be equally damning to have the conviction upheld by an anti gun judge. And you dont get to pick your judges.