It was the Heide Knight Sword. It's move motion even looks like it sweeps up so it should hit the super low enemies like those hollows that crawl on the ground but still totally whiffs. I made that post raging about the Rat Authority boss. The boss itself was fine, it was the four little rats that cause toxic that were driving me nuts. I finally beat it though. Just have the Iron Keep left to get the four major souls to move on to the second half of the game.
What weapon are you using? The Large weapons you can continue to aim them after you start the swing. I believe it's the left stick. So if they start in front and zip to your right after you wind up your swing, you can manually correct the swing by pressing the stick to the right. Ultra great swords, great axes, and great hammers can be aimed. So if you are moving awhile swinging it won't necessarily swing at what you are locked on to. If you plant your feet and don't touch the stick, then it will swing at the direction of the lock-on.
I thought it went toward the enemy you point to with the stick, but it has been awhile. What happens when you press down, or Down-left / down-right?
I haven't tried pushing down, I'll see if that makes it better. I usually just flick the stick left or right.