The balancing factor for a cleric gaining spells was the limit to blunt weapons (most of which capped a 1d6, vs 1d8 or 1d10 for most swords) and the fact they had little or no combat-ready spells (excluding cause/inflict X wounds).
Since originally all weapons did 1d6 damage, I think the limitation on weapons was more to keep the cleric from claiming magic items the game intended to go to fighters.
It amounts to the same thing, though. The best, most common magic weapons were swords giving the fighting-men an advantage in melee over the clerics and magic-users.