Minecraft wiki entry for Heads-up_display, associated text: If the option for the attack indicator is set to "Crosshair" mode, weapon cooldown time is indicated by a sword icon near the crosshair that fills, representing the cooldown progress. This sword icon disappears once the weapon is fully cooled. In this mode, if a fully cooled weapon is being held, and a mob or player is in range, the sword icon and an additional plus-sign (+) indicator is shown below the crosshair, indicating that the weapon is in range to land a full-damage blow.‌[Java Edition only]