Both. I was curious about this too. I rested up and walked right up to a rev and started swinging. I was getting hit long before I was able to hit. Revenant was unarmed, I was using picks. Had to practically stand on the creature's toes. In running / moving combat, I can't hit the creature unless I actually run into it as I swing. If I try to keep away out of it's reach I cannot hit it, but it hits me from distances that seem impossible.
Frustrating, because all I can really do if I want to damage a revenant is stand there toe and trade shots with it, which doesn't end well as they have 3 to 4 times my HP.