I'm wondering if we're going too far with this policy. A fundamental need of children is to feel safe. However, this kind of outright banning of such items can backfire unless it is part of a larger effort to teach social responsibility within the school. Many children receive such conflicting messages about weapons and violence that figuring out how to behave can present a real dilemma. As our mass culture provides more models of violent and other antisocial behavior, schools can fill a vital need by helping children learn to be contributing members of a caring and peaceful community.
Violence is a learned behavior and hence can be unlearned.
But this takes a concerted effort such as the one your school is making. They're getting ready for standardized tests and the whole class seems quite anxious. Just mentioning the upcoming tests makes many of my students look visibly nervous. One easy stress management technique to teach kids is the relaxation skill of deep breathing. We all think we know how to take deep breaths, but that's not always true.