I have a small necklace knife where the blade is less than 1 inch or 2 1/2 cm I live in Washington and go to high school would it be legal to carry such a small knife in a pocket in my backpack? it is under the requirement for "deadly" as it is way too small to really hurt someone.
RCW 9.41.280 prohibits firearms and "dangerous weapons", which does not extend to a tiny knife. Seattle Public Schools does not add anything relevant above state law, nor does Renton, nor Bellevue. Bellevue just says "knives" which is broader than state law, but they refer the question to state law, and such a "knife" would not be a dangerous weapon under state law. Seattle Prep doesn't say explicitly and doesn't refer the question to state law. There are hundreds of schools, so you'd have to check the specific school. Incidentally, if you concludes based on reading the school's policy that it is not prohibited, they may still punish you (confiscating the knife is more likely), and you may have to sue them to abide by their published policy. Their defense could simply be "we consider all knives to be dangerous weapons".