Combat Toggle

This icon looks like either a bow or a sword. When it looks like a bow, you tap it to switch to melee combat. When it looks like a sword, tap it to change it to ranged attack. This icon means nothing in itself. It simply will tell the combat engine which weapon takes precedence. You may have it set to ranged combat and not actually have a ranged weapon. If that is the case the combat engine will seek to use your melee weapon instead (if you have on equipped). The opposite is also true. You do not need to be more than one square away to attack someone with a ranged weapon.