I don't have the cite, but I think it says something like "allows it to be drawn in the open position".
Found this quickly
At a Glance:
The body of Massachusetts law concerning knives is not easily capsulized. The primary statute regarding the possession and carrying of knives, found at 269 § 10 sub-section (b), is a single sentence consisting of almost 400 words. It states that one may not “carry on his person” – including in a vehicle – any: stiletto, dagger, ballistic knife, dirk knife, automatic knife having a blade longer than one and a half (1 ½) inches, knife with a double-edged blade, or device which enables a knife with a locking blade to be drawn at a locked position. This list of knives may be referred to as the per se or “by definition” prohibited knives, although there are no statutory definitions.
[URL unfurl="true"]https://www.akti.org/state-knife-laws/massachusetts/[/URL]
ETA: lower in the above link, so maybe not. But we all know how the laws are interpreted here
Blade Drawn at Open and Locked Position
Massachusetts prohibits the carry of any device which allows a knife with a locking blade to be drawn at the locked position. This was evidently intended to proscribe quick draw sheaths marketed for manually opened lock-blade knives such as the iconic Buck Model 110. While such “quick draw” devices have become uncommon, Massachusetts prosecuting officials have attempted to apply this prohibition to one-hand manual knives with “thumb studs” as well as “butterfly” knives without any associated sheath or other device!
I think a device is a separate item, not a blade feature... But I'm just a commoner...
