We see a new box on hand

What were your skin settings, especially "Right sleeve"
Can you please attach your skin file ?

Please force a crash by pressing F3 + C for 10 seconds while in-game and attach the crash report ([minecraft/crash-reports/crash-<DATE>-client.txt|http://hopper.minecraft.net/help/finding-minecraft-data-folder]) here.

Go to settings then in skin customization then turn everything off (only works in 1.8)
and it will disappear.