Gloves
You need to bring one thick warm pair and one thin backup pair. The thick pair can be anything from basic padded ski gloves to the more expensive specific mountaineering type; the thin pair can be much thinner and lighter, to be used when it’s warmer and also in case you drop your thick ones. The combination of mittens and thin gloves together also works, but be aware that you will have to take off the mittens every time you need to put crampons on, take pictures, etc.