ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-OmaHe28t4uk.html I forgot to put my stats in the video, so this video is all my melds, food and potions.
My best guess is that's a visual timer for when your weaponskill combo is about to fall off, since you can stall out doing combo hits for up to 30s before it falls off and you have to start over.