HI! I'm the first from Mass, hate seeing that NEVER under threads. I hope to see more locals posting. Looking forward to discussing everything handguns and CCW! Difficult as it can be here in the Peoples Republic!
There are many laws...no double edged weapons etc but I believe there is not a limitation as stipulated under Mass laws for blade size except for spring loaded or assisted (switchblades) which are not allowed with blades over 1 1/2 inches. I wouldn't even tempt fate with one that small.
Most citys and towns have local ordinances that are enforced at the whim of the local police. It seems that the norm is anything with a blade under 2 1/2 inches is okay. I've seen people "working" and carrying a leatherman with a much larger blade and they are not bothered but I wouldn't expect anyone to try to pull a knife blade out of a leatherman with any speed for an attack or self-defence 8~)
Keep it under 2 1/2 inches and I think he should be okay. Try a google search for Massachusetts Gun Laws and you may find it in detail.