Campbell also called for “better collaboration in the information shared between social services and school leaders”.
He said “clearly the person was a troubled individual, that came out in court. We need to ask about support for mental health issues”.
The teenager was found guilty of the attempted murder of teachers Fiona Elias and Liz Hopkin and a pupil at Ysgol Dyffryn Aman in April 2024.
They were all taken to hospital after the attack.
Campbell said while he did not really know what the answer was, it needed careful attention because knife crime and violence against teachers had increased since the Covid-19 pandemic.
He said “searching pupils is one solution” to prevent such an incident from happening again but he questioned “whether teachers want to play that role of playing security guard as well as being teachers”.
He warned this could lead to confrontations and said another option might be for schools to employ “specialist security guards”.
Campbell said “teachers shouldn’t feel threatened in any way”, adding teaching unions needed to be consulted on any plans to ask teachers to check bags.
“What we don’t want to do is to go down the road of some American states and cities where there are scanners and body scanners for everyone going into school every day metal detectors,” he said.
He said pupils as young as year two – aged six and seven – carrying knives was “an extremely sad indictment of our society and I have no doubt that social media plays a part in this as well”.
Existing Welsh government legislation says “reasonable force” may be used without pupils’ consent to search for weapons.