FWIW, I've been trying to figure this out myself for a while now. I've read the code several times and parts of it still seem rather vague to me. I couldn't say whether it's legal or not, but I wouldn't carry a fixed blade on school grounds. My sister's a teacher and with all the silly things that the teachers get hassled for by administrators, I could imagine what would happen if one was spotted with a fixed blade, no matter how small.
I probably would stick to nothing more threatening (won't get into the issue of scissors and other pointy school supplies here) than a Vic Classic on school grounds, at least until I could get a clear answer on that section of the code. And even then I wouldn't want most of the students to see it. Sad? Yes. But kids gossip and I wouldn't want my name dragged through the news over a tiny knife that I was using to open an envelope.
Wanted to add: Sorry I couldn't actually help.