No one should ever feel the need to take weapons into schools. Doing so is likely to be a criminal offence. Schools have a statutory power to search for and confiscate prohibited items such as knives and weapons.
The Department has produced advice for schools which makes it clear that school staff can search pupils or their possessions, without consent, where there are reasonable grounds to do so. The guidance is available at: https://www.gov.uk/government/publications/searching-screening-and-confiscation. If a pupil refuses to be searched, the school may bar them from the premises.
The Department is working with the Home Office to consider how we can reinforce the message that it is unacceptable to bring knives or weapons into schools. As part of this work, the Department is considering how it can further strengthen the advice and support it provides to schools.