I personally have never heard of low amperage (household light and outlet breakers causing arc flash.
however when resetting a large amperage (industrial) breaker into a dead short a big arc results. the breaker could weld shut untill a meltdown occurs, but normally it will just pop open again. when it pops, there is a giant arc. in arc flash, the arc ionizes the air and makes it conductive. even though the breaker is open, the ionized air is arcing and carrying current accross the opened points of the breaker. this arcing makes even more ionized air. eventually the ionized air fills the breaker panel. arc flash then starts to occur accross the bus bars in the panel. the air is heated so quickly that the only way for it to escape the panel is to blow the front off. I have also heard that the massive amount of heat and the arcing will even dissosiate (split) the hydrogen and oxygen from moisture in the air and any condensation in the panel. if that is true, your panel basically turns into a hydrogen bomb
