So here's a weird problem. I've searched the internet and cannot find anyone else with this problem.
When I swing with just one glove on my left hand, I have a hard time making good contact with the ball. I often blade it, no matter what iron I'm using. On impact, I can feel the club slip in my hands and it feels like I may let go. Sometimes the club will even rotate so that the club face is maybe 15-30 degrees closed. With one glove, I almost never hit it as far or as high in the air as I can.
This problem started just this year in the early parts of the season. It has not happened all year. I could feel the club slipping in my hands, so I decided to see what happened if I wore two gloves. I bought a glove for my right hand, put both of them on, and ta-da, the problem was fixed. I hit my irons straight, long (for me), and with a nice trajectory. Ever since, I've been playing fine with two gloves.
At the range this week, I decided to see what happens if I try just one glove again (I was thinking maybe the two gloves was just placebo, and I fixed my grip somehow), so I wore a glove on my left hand only, and the same problem continued. I can feel club rotate in my hands, which results in a hook and usually topping the ball.
This problem only happens when I wear one glove. With a glove on each hand, it never happens.