Hi,
looks like your son has just about everything you could expect him to carry. Bullying is the pits, I'm glad you seem to have a way forward.

Two possible suggestions: a list of contact phone numbers for him to carry and a mini whistle.

I've got a few mini whistles on order (no affiliations) for my kids (and me).
They can be threaded to make a paracord pull tab which I'll attach to their jackets, bags and I'll put one on their keyrings. They are surprisingly loud for their size.

(I hope this picture works)