I did not make note of the article I read this on, but I wanted to get this scrawled note from an index card recorded so I can ditch the index card. I believe this is the article, but there’s no date on it, so I’m not sure.
It discussed the arbalest, a heavy crossbow, that used spring steel arms for the bow and had a range of about 300 meters, longer than 3 American football fields! It also had a fire rate of 2/minute.
They could shoot bolts or stones or shot. I’ll have to dig up the article, but it would be a heavy+ crossbow in D&D terms. Since a longbow is often credited as 12 aimed shots a minute and that is translated to 2 shots per round in AD&D, it makes sense that one shot per round for an arbalest. The heavy crossbow has a more complex cocking procedure, so one shot every other round.
Or is an arbalest just one expression of what the heavy crossbow in AD&D represents?
I mentioned in two past articles (one, two) about my brother, Robert, allowing a Chinese style self loading crossbow that could fire 10 shots a round, and our foolish characters ended up as orc food because we elected to fight with swords instead of our cool crossbows.
Finding the proper scale so that one isn’t dropping a combat changer into the midst of the game is the only part of balance I am concerned with.
In general play, I’d class the arbalest as a heavy x-bow, in that it requires a crank to bend the prod. I’d consider a light crossbow as being able to be drawn either by hand or with the assistance of a stirrup/cocking lever. The wiki article also refers to the 2/minute firing rate, but I’d be skeptical, especially if the crank was not integral to the bow.
Although here’s a guy cranking a 1250-lb (!) draw bow. He’s able to loose two rounds in about 45 seconds.
https://www.youtube.com/watch?v=WEOeZTV9wiA
From looking at his various crossbow videos, I guess I’d divide the light vs heavy at about 400-450 lbs draw weight (based on draw methods).
The underlying issue is the gaming model of the ‘combat round’ which appears to vary between 6 seconds and one minute, depending your your rule-set. As you mentioned, a consistency of scale is probably more important than the ‘realistic’ qualities of a particular weapon or combat method.