Was the reason for issuance of Cannon 29 in the Second Lateran Council by Pope Innocent II, which decreed a ban on missile weapons (crossbows in particular) against Christians based on ethical grounds or on the fact that the crossbow's ease of use gave it something of a potential as an equalizer because it required relatively little training, skill or funds to use and made it a threat to the established social order of the time?
Closer to the first than the second, although neither interpretation is particularly accurate. I go into detail about why in this thread. In short, the "ban" on ranged weaponry was not really equivalent to modern legal restrictions on weaponry. Nor is the idea of the crossbow as an "equalizer" either accurate or something that contemporary crossbowmen would have agreed with. Crossbows were not cheap, they did not require less skill to use than other weapons, and they were not a threat to the established social order. If we were going to stereotype the typical crossbowman on the medieval battlefield, he would probably be an urban burgher or townsman rather a peasant.