Wow, Conjured Entertainment. Haven't seen you around for awhile. I'm not visiting as often now either but thought I would check to see what you were up to.
It could be used as a boolean. I started looking at this in the code and will let y'all know.
Addendum #1
It is somewhat confusing at first as it usually is.
I believe it is a condition meant for any one of the players weapon. This condition was created very early on and probably in v1.0. I also believe it probably was one of those commands Lee meant to revisit later and probably never did. It definitely doesn't work now and it won't because it has to be associated with a player's weapon. Instead, it always is associated with the entity that contains the script with the quantity condition. So, if you put it in a trigger zone it will always compare the quantity value in the script with 0. If an NPC it will always be compared to 1.
I will continue to look at it later and check out if the variable that the quantity is stored in changes or not throughout the game. I have to add some code to write to a log file for this.
Right now, I would venture an educated guess that this command is dead.
THEORY - you know everything but nothing works. PRACTICE - when everything works but don't know why. For me, theory and practice are combined: nothing works and I don't know why.