Does not having a DR breaking weapon affect your chance to hit a mob?

I've had a couple characters where changing from a non DR breaker to a DR breaking weapon dramatically increases the hit rate.

Most recently I have a cleric who is not a very good melee toon. However, he usually swings a mace if he has nothing better to do. While fighting an elite Shavarath bearded devil with a +1 impellent, greater poison mace a large majority of his swings did no damage (glancing blow with DR dropping it to 0, no proc). When I switched to a +2 Shock of Pure Good, most of the swings were full hits. No other changes, just a weapon change. The 1 extra enchantment couldn't possibly result in the difference in hits I was seeing.

It was particularly obvious because with no procs on the glancing blows, the impellent weapon was line after line of 0s with an occasional line doing damage, while the holy one had pretty fat damage lines

I've also noticed it on my druid versus skeletons. When in wolf form, lots of glancing blows. Switch to human or elemental (with the same blunt weapon I was using in wolf form) and suddenly I start hitting fine. It was more obvious the weaker the toon was in melee, but it seems to be a pretty large effect.

Anyone else experience this? Is there a thread I missed that describes the effect?
And does it affect mobs attacking players?